diff --git a/erpnext/hr/doctype/additional_salary/additional_salary.py b/erpnext/hr/doctype/additional_salary/additional_salary.py
index d8f7444..4076ffe 100644
--- a/erpnext/hr/doctype/additional_salary/additional_salary.py
+++ b/erpnext/hr/doctype/additional_salary/additional_salary.py
@@ -9,6 +9,13 @@
 from frappe.utils import getdate, date_diff
 
 class AdditionalSalary(Document):
+
+	def on_submit(self):
+		if self.ref_doctype == "Employee Advance" and self.ref_docname:
+			emp_adv = frappe.get_doc(self.ref_doctype, self.ref_docname)
+			emp_adv.return_amount = self.amount
+			emp_adv.save()
+
 	def before_insert(self):
 		if frappe.db.exists("Additional Salary", {"employee": self.employee, "salary_component": self.salary_component,
 			"amount": self.amount, "payroll_date": self.payroll_date, "company": self.company, "docstatus": 1}):
@@ -49,8 +56,8 @@
 
 @frappe.whitelist()
 def get_additional_salary_component(employee, start_date, end_date, component_type):
-	additional_components = frappe.db.sql("""
-		select name, salary_component, amount, overwrite_salary_structure_amount, deduct_full_tax_on_selected_payroll_date
+	additional_salaries = frappe.db.sql("""
+		select name, salary_component, type, amount, overwrite_salary_structure_amount, deduct_full_tax_on_selected_payroll_date
 		from `tabAdditional Salary`
 		where employee=%(employee)s
 			and docstatus = 1
@@ -60,7 +67,7 @@
 					from_date <= %(to_date)s and to_date >= %(to_date)s
 				)
 		and type = %(component_type)s
-		order by salary_component, overwrite_salary_structure_amount
+		order by salary_component, overwrite_salary_structure_amount DESC
 	""", {
 		'employee': employee,
 		'from_date': start_date,
@@ -68,26 +75,38 @@
 		'component_type': "Earning" if component_type == "earnings" else "Deduction"
 	}, as_dict=1)
 
-	additional_components_list = []
-	existing_salary_components = []
+	existing_salary_components= []
+	salary_components_details = {}
+	additional_salary_details = []
+
+	overwrites_components = [ele.salary_component for ele in additional_salaries if ele.overwrite_salary_structure_amount == 1]
+
 	component_fields = ["depends_on_payment_days", "salary_component_abbr", "is_tax_applicable", "variable_based_on_taxable_salary", 'type']
-	for d in additional_components:
-		if d.salary_component in existing_salary_components:
-			frappe.throw(_('Multiple additional Salary is created for Salary Component {0}'.format(d.salary_component)))
-		struct_row = frappe._dict({'salary_component': d.salary_component})
-		component = frappe.get_all("Salary Component", filters={'name': d.salary_component}, fields=component_fields)
-		if component:
-			struct_row.update(component[0])
+	for d in additional_salaries:
 
-		struct_row['deduct_full_tax_on_selected_payroll_date'] = d.deduct_full_tax_on_selected_payroll_date
-		struct_row['is_additional_component'] = 1
-		struct_row['additional_salary'] = d.name
+		if d.salary_component not in existing_salary_components:
+			component = frappe.get_all("Salary Component", filters={'name': d.salary_component}, fields=component_fields)
+			struct_row = frappe._dict({'salary_component': d.salary_component})
+			if component:
+				struct_row.update(component[0])
 
-		additional_components_list.append(frappe._dict({
-			'amount': d.amount,
-			'type': component[0].type,
-			'struct_row': struct_row,
-			'overwrite': d.overwrite_salary_structure_amount,
-		}))
+			struct_row['deduct_full_tax_on_selected_payroll_date'] = d.deduct_full_tax_on_selected_payroll_date
+			struct_row['is_additional_component'] = 1
+
+			salary_components_details[d.salary_component] = struct_row
+
+
+		if overwrites_components.count(d.salary_component) > 1:
+			frappe.throw(_("Multiple Additional Salaries with overwrite property exist for Salary Component: {0} between {1} and {2}.".format(d.salary_component, start_date, end_date)), title=_("Error"))
+		else:
+			additional_salary_details.append({
+				'name': d.name,
+				'component': d.salary_component,
+				'amount': d.amount,
+				'type': d.type,
+				'overwrite': d.overwrite_salary_structure_amount,
+			})
+
 		existing_salary_components.append(d.salary_component)
-	return additional_components_list
\ No newline at end of file
+
+	return salary_components_details, additional_salary_details
\ No newline at end of file
diff --git a/erpnext/hr/doctype/employee_advance/employee_advance.json b/erpnext/hr/doctype/employee_advance/employee_advance.json
index 1ab2356..8c5ce42 100644
--- a/erpnext/hr/doctype/employee_advance/employee_advance.json
+++ b/erpnext/hr/doctype/employee_advance/employee_advance.json
@@ -165,6 +165,7 @@
    "options": "Mode of Payment"
   },
   {
+   "allow_on_submit": 1,
    "fieldname": "return_amount",
    "fieldtype": "Currency",
    "label": "Returned Amount",
@@ -180,7 +181,7 @@
  ],
  "is_submittable": 1,
  "links": [],
- "modified": "2020-03-05 16:31:50.417539",
+ "modified": "2020-03-06 15:11:33.747535",
  "modified_by": "Administrator",
  "module": "HR",
  "name": "Employee Advance",
diff --git a/erpnext/hr/doctype/employee_incentive/employee_incentive.py b/erpnext/hr/doctype/employee_incentive/employee_incentive.py
index 1cc52e1..44763fc 100644
--- a/erpnext/hr/doctype/employee_incentive/employee_incentive.py
+++ b/erpnext/hr/doctype/employee_incentive/employee_incentive.py
@@ -9,27 +9,13 @@
 class EmployeeIncentive(Document):
 	def on_submit(self):
 		company = frappe.db.get_value('Employee', self.employee, 'company')
-		additional_salary = frappe.db.exists('Additional Salary', {
-				'employee': self.employee,
-				'ref_doctype': self.doctype,
-				'ref_docname': self.name,
-				'salary_component': self.salary_component,
-				'payroll_date': self.payroll_date,
-				'company': company,
-				'docstatus': ["!=", 2]
-			})
 
-		if not additional_salary:
-			additional_salary = frappe.new_doc('Additional Salary')
-			additional_salary.employee = self.employee
-			additional_salary.salary_component = self.salary_component
-			additional_salary.amount = self.incentive_amount
-			additional_salary.payroll_date = self.payroll_date
-			additional_salary.company = company
-			additional_salary.ref_doctype = self.doctype
-			additional_salary.ref_docname = self.name
-			additional_salary.submit()
-		else:
-			incentive_added = frappe.db.get_value('Additional Salary', additional_salary, 'amount') + self.incentive_amount
-			frappe.db.set_value('Additional Salary', additional_salary, {'amount', incentive_added})
-
+		additional_salary = frappe.new_doc('Additional Salary')
+		additional_salary.employee = self.employee
+		additional_salary.salary_component = self.salary_component
+		additional_salary.amount = self.incentive_amount
+		additional_salary.payroll_date = self.payroll_date
+		additional_salary.company = company
+		additional_salary.ref_doctype = self.doctype
+		additional_salary.ref_docname = self.name
+		additional_salary.submit()
diff --git a/erpnext/hr/doctype/leave_encashment/leave_encashment.py b/erpnext/hr/doctype/leave_encashment/leave_encashment.py
index ad2cc02..56f2f4c 100644
--- a/erpnext/hr/doctype/leave_encashment/leave_encashment.py
+++ b/erpnext/hr/doctype/leave_encashment/leave_encashment.py
@@ -31,13 +31,16 @@
 		additional_salary = frappe.new_doc("Additional Salary")
 		additional_salary.company = frappe.get_value("Employee", self.employee, "company")
 		additional_salary.employee = self.employee
-		additional_salary.salary_component = frappe.get_value("Leave Type", self.leave_type, "earning_component")
+		earning_component = frappe.get_value("Leave Type", self.leave_type, "earning_component")
+		if not earning_component:
+			frappe.throw(_("Please set Earning Component for Leave type: {0}.".format(self.leave_type)))
+		additional_salary.salary_component = earning_component
 		additional_salary.payroll_date = self.encashment_date
 		additional_salary.amount = self.encashment_amount
+		additional_salary.ref_doctype = self.doctype
+		additional_salary.ref_docname = self.name
 		additional_salary.submit()
 
-		self.db_set("additional_salary", additional_salary.name)
-
 		# Set encashed leaves in Allocation
 		frappe.db.set_value("Leave Allocation", self.leave_allocation, "total_leaves_encashed",
 				frappe.db.get_value('Leave Allocation', self.leave_allocation, 'total_leaves_encashed') + self.encashable_days)
@@ -119,4 +122,4 @@
 			leave_type=allocation.leave_type,
 			encashment_date=allocation.to_date
 		))
-		leave_encashment.insert(ignore_permissions=True)
+		leave_encashment.insert(ignore_permissions=True)
\ No newline at end of file
diff --git a/erpnext/hr/doctype/salary_slip/salary_slip.py b/erpnext/hr/doctype/salary_slip/salary_slip.py
index ac55c67..1d19427 100644
--- a/erpnext/hr/doctype/salary_slip/salary_slip.py
+++ b/erpnext/hr/doctype/salary_slip/salary_slip.py
@@ -74,7 +74,6 @@
 	def on_cancel(self):
 		self.set_status()
 		self.update_status()
-		self.update_salary_slip_in_additional_salary()
 		self.cancel_loan_repayment_entry()
 
 	def on_trash(self):
@@ -405,14 +404,15 @@
 						self.update_component_row(frappe._dict(last_benefit.struct_row), amount, "earnings")
 
 	def add_additional_salary_components(self, component_type):
-		additional_components = get_additional_salary_component(self.employee,
+		salary_components_details, additional_salary_details = get_additional_salary_component(self.employee,
 			self.start_date, self.end_date, component_type)
-		if additional_components:
-			for additional_component in additional_components:
-				amount = additional_component.amount
-				overwrite = additional_component.overwrite
-				self.update_component_row(frappe._dict(additional_component.struct_row), amount,
-					component_type, overwrite=overwrite)
+		if salary_components_details and additional_salary_details:
+			for additional_salary in additional_salary_details:
+				additional_salary =frappe._dict(additional_salary)
+				amount = additional_salary.amount
+				overwrite = additional_salary.overwrite
+				self.update_component_row(frappe._dict(salary_components_details[additional_salary.component]), amount,
+					component_type, overwrite=overwrite, additional_salary=additional_salary.name)
 
 	def add_tax_components(self, payroll_period):
 		# Calculate variable_based_on_taxable_salary after all components updated in salary slip
@@ -432,21 +432,20 @@
 			tax_row = self.get_salary_slip_row(d)
 			self.update_component_row(tax_row, tax_amount, "deductions")
 
-	def update_component_row(self, struct_row, amount, key, overwrite=1):
+	def update_component_row(self, struct_row, amount, key, overwrite=1, additional_salary = ''):
 		component_row = None
 		for d in self.get(key):
 			if d.salary_component == struct_row.salary_component:
 				component_row = d
-
-		if not component_row:
+		if not component_row or (struct_row.get("is_additional_component") and not overwrite):
 			if amount:
 				self.append(key, {
 					'amount': amount,
-					'additional_salary': '' if not struct_row.get("additional_salary") else struct_row.get("additional_salary"),
 					'default_amount': amount if not struct_row.get("is_additional_component") else 0,
 					'depends_on_payment_days' : struct_row.depends_on_payment_days,
 					'salary_component' : struct_row.salary_component,
 					'abbr' : struct_row.abbr,
+					'additional_salary': additional_salary,
 					'do_not_include_in_total' : struct_row.do_not_include_in_total,
 					'is_tax_applicable': struct_row.is_tax_applicable,
 					'is_flexible_benefit': struct_row.is_flexible_benefit,
@@ -458,6 +457,7 @@
 			if struct_row.get("is_additional_component"):
 				if overwrite:
 					component_row.additional_amount = amount - component_row.get("default_amount", 0)
+					component_row.additional_salary = additional_salary
 				else:
 					component_row.additional_amount = amount
 
@@ -878,4 +878,4 @@
 
 def generate_password_for_pdf(policy_template, employee):
 	employee = frappe.get_doc("Employee", employee)
-	return policy_template.format(**employee.as_dict())
+	return policy_template.format(**employee.as_dict())
\ No newline at end of file