diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.js b/erpnext/buying/doctype/purchase_order/purchase_order.js
index 7c33056..f6a1951 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.js
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.js
@@ -185,8 +185,7 @@
 
 			if(!in_list(["Closed", "Delivered"], doc.status)) {
 				if(this.frm.doc.status !== 'Closed' && flt(this.frm.doc.per_received, 2) < 100 && flt(this.frm.doc.per_billed, 2) < 100) {
-					// Don't add Update Items button if the PO is following the new subcontracting flow.
-					if (!(this.frm.doc.is_subcontracted && !this.frm.doc.is_old_subcontracting_flow)) {
+					if (!this.frm.doc.__onload || this.frm.doc.__onload.can_update_items) {
 						this.frm.add_custom_button(__('Update Items'), () => {
 							erpnext.utils.update_child_items({
 								frm: this.frm,
diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.py b/erpnext/buying/doctype/purchase_order/purchase_order.py
index 06b9d29..4da1e76 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.py
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.py
@@ -49,9 +49,22 @@
 			}
 		]
 
+	def can_update_items(self) -> bool:
+		result = True
+
+		if self.is_subcontracted and not self.is_old_subcontracting_flow:
+			# Check - 1: NOT ALLOWED if non-cancelled Subcontracting Order exists for this Purchase Order
+			if frappe.db.exists(
+				"Subcontracting Order", {"purchase_order": self.name, "docstatus": ["!=", 2]}
+			):
+				return False
+
+		return result
+
 	def onload(self):
 		supplier_tds = frappe.db.get_value("Supplier", self.supplier, "tax_withholding_category")
 		self.set_onload("supplier_tds", supplier_tds)
+		self.set_onload("can_update_items", self.can_update_items())
 
 	def validate(self):
 		super(PurchaseOrder, self).validate()
diff --git a/erpnext/public/js/utils.js b/erpnext/public/js/utils.js
index f456e5e..9116fd1 100755
--- a/erpnext/public/js/utils.js
+++ b/erpnext/public/js/utils.js
@@ -678,6 +678,37 @@
 		})
 	}
 
+	if (frm.doc.doctype == 'Purchase Order' && frm.doc.is_subcontracted && !frm.doc.is_old_subcontracting_flow) {
+		fields.push({
+			fieldtype:'Link',
+			fieldname:'fg_item',
+			options: 'Item',
+			reqd: 1,
+			in_list_view: 0,
+			read_only: 0,
+			disabled: 0,
+			label: __('Finished Good Item'),
+			get_query: () => {
+				return {
+					filters: {
+						'is_stock_item': 1,
+						'is_sub_contracted_item': 1,
+						'default_bom': ['!=', '']
+					}
+				}
+			},
+		}, {
+			fieldtype:'Float',
+			fieldname:'fg_item_qty',
+			reqd: 1,
+			default: 0,
+			read_only: 0,
+			in_list_view: 0,
+			label: __('Finished Good Item Qty'),
+			precision: get_precision('fg_item_qty')
+		})
+	}
+
 	let dialog = new frappe.ui.Dialog({
 		title: __("Update Items"),
 		size: "extra-large",