diff --git a/sale_stock_product_pack/models/__init__.py b/sale_stock_product_pack/models/__init__.py
index 6aacb7531..2d7ee6c3d 100644
--- a/sale_stock_product_pack/models/__init__.py
+++ b/sale_stock_product_pack/models/__init__.py
@@ -1 +1,2 @@
 from . import sale_order
+from . import sale_order_line
diff --git a/sale_stock_product_pack/models/sale_order.py b/sale_stock_product_pack/models/sale_order.py
index 02df5ff1b..c9fd7e96a 100644
--- a/sale_stock_product_pack/models/sale_order.py
+++ b/sale_stock_product_pack/models/sale_order.py
@@ -4,28 +4,39 @@
 from odoo import models
 
 
-class SaleOrderLine(models.Model):
-    _inherit = "sale.order.line"
+class SaleOrder(models.Model):
+    _inherit = "sale.order"
 
-    def _compute_qty_delivered(self):
-        """Compute pack delivered pack quantites according to its components
-        deliveries"""
-        super()._compute_qty_delivered()
-        main_pack_lines = self.filtered("pack_parent_line_id").mapped(
-            "pack_parent_line_id"
-        )
-        for line in main_pack_lines.filtered(
-            lambda x: x.qty_delivered_method == "stock_move"
-            and x.pack_child_line_ids
-            and x.product_uom_qty
-        ):
-            delivered_packs = []
-            # We filter non qty lines of editable packs
-            for pack_line in line.pack_child_line_ids.filtered("product_uom_qty"):
-                # If a component isn't delivered, the pack isn't as well
-                if not pack_line.qty_delivered:
-                    delivered_packs.append(0)
-                    break
-                qty_per_pack = pack_line.product_uom_qty / line.product_uom_qty
-                delivered_packs.append(pack_line.qty_delivered / qty_per_pack)
-            line.qty_delivered = delivered_packs and min(delivered_packs) or 0.0
+    def _get_invoiceable_lines(self, final=False):
+        """Override to ensure pack parent lines are included when their
+        components are being invoiced/refunded.
+
+        When processing returns, only component lines have stock moves, so only
+        they would be included in the refund. This method ensures that if pack
+        component lines are invoiceable (due to returns), their parent pack line
+        is also included if it has a price.
+        """
+        lines = super()._get_invoiceable_lines(final=final)
+        pack_components_in_lines = lines.filtered("pack_parent_line_id")
+        if pack_components_in_lines:
+            pack_parent_lines = pack_components_in_lines.mapped("pack_parent_line_id")
+            has_return = any(
+                comp.qty_to_invoice < 0 for comp in pack_components_in_lines
+            )
+            additional_pack_lines = pack_parent_lines.filtered(
+                lambda x: x.id not in lines.ids
+                and (x.pack_component_price != "detailed" or x.price_unit > 0)
+                and (x.qty_to_invoice != 0 or (x.qty_invoiced > 0 and has_return))
+            )
+            if additional_pack_lines:
+                result_lines = self.env["sale.order.line"]
+                for line in lines:
+                    result_lines |= line
+                    if (
+                        line.pack_parent_line_id
+                        and line.pack_parent_line_id in additional_pack_lines
+                    ):
+                        result_lines |= line.pack_parent_line_id
+                        additional_pack_lines -= line.pack_parent_line_id
+                return result_lines
+        return lines
diff --git a/sale_stock_product_pack/models/sale_order_line.py b/sale_stock_product_pack/models/sale_order_line.py
new file mode 100644
index 000000000..166fe6eb0
--- /dev/null
+++ b/sale_stock_product_pack/models/sale_order_line.py
@@ -0,0 +1,59 @@
+# Copyright 2021 Tecnativa - David Vidal
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+# pylint: disable=W8110
+from odoo import models
+
+
+class SaleOrderLine(models.Model):
+    _inherit = "sale.order.line"
+
+    def _compute_qty_delivered(self):
+        """Compute pack delivered pack quantites according to its components
+        deliveries"""
+        super()._compute_qty_delivered()
+        main_pack_lines = self.filtered("pack_parent_line_id").mapped(
+            "pack_parent_line_id"
+        )
+        for line in main_pack_lines.filtered(
+            lambda x: x.qty_delivered_method == "stock_move"
+            and x.pack_child_line_ids
+            and x.product_uom_qty
+        ):
+            delivered_packs = []
+            # We filter non qty lines of editable packs
+            for pack_line in line.pack_child_line_ids.filtered("product_uom_qty"):
+                # If a component isn't delivered, the pack isn't as well
+                if not pack_line.qty_delivered:
+                    delivered_packs.append(0)
+                    break
+                qty_per_pack = pack_line.product_uom_qty / line.product_uom_qty
+                delivered_packs.append(pack_line.qty_delivered / qty_per_pack)
+            line.qty_delivered = delivered_packs and min(delivered_packs) or 0.0
+
+    def _prepare_invoice_line(self, **optional_values):
+        """Override to handle pack lines in returns.
+
+        When a return is being processed, pack parent lines don't have stock moves,
+        so their qty_delivered doesn't update automatically. We need to calculate
+        the correct quantity based on the components being returned.
+        """
+        res = super()._prepare_invoice_line(**optional_values)
+        if self.pack_child_line_ids and self.product_id.pack_ok:
+            components_being_returned = self.pack_child_line_ids.filtered(
+                lambda x: x.qty_to_invoice < 0
+            )
+            if components_being_returned and res.get("quantity", 0) == 0:
+                refund_quantities = []
+                for comp in components_being_returned:
+                    qty_per_pack = (
+                        comp.product_uom_qty / self.product_uom_qty
+                        if self.product_uom_qty
+                        else 0
+                    )
+                    if qty_per_pack:
+                        packs_to_refund = comp.qty_to_invoice / qty_per_pack
+                        refund_quantities.append(packs_to_refund)
+                if refund_quantities:
+                    pack_qty_to_refund = max(refund_quantities)
+                    res["quantity"] = pack_qty_to_refund
+        return res