Configuration for merge manufacturing orders, here you can choose merge type and if you tick the "Notify in Chatter" option then it gives notification of merged orders into the chatter.

"Merge MRP Orders" menu and tree view.

You can merge only draft/ confirmed/ in-progress state orders.

You can merge MRP orders which have the same product/bill of materials.

Merge manufacturing orders wizard with the default selected merge type.

Merge manufacturing orders wizard with the existing order type.

We merge the manufacturing orders with the default selected merge type.

Here it creates a new order and cancels selected orders.

The merged MRP order form view.

Merged orders notification comes into the chatter.

Enable "Subtract Merged Quantity".

Select two or more order and click merge MRP orders.

So it opens merge MRP order wizard with all records quantity & on-hand qty. You can subtract qty from this wizard as well.

Created order list view.

New generated MRP order looks like below.

Old order with remaining quantity.

If you try to add qty more than order line qty then alert occurs.

Go to users and tick "Dynamic Merge Chatter Message".

Here, is the list view of the manufacturing orders.
Select the manufacturing orders. After that, Click on the " Merge MRP Orders" option.

After that "Merge MRP Orders" wizard will appear.
Enable the "Is Merge Chatter Message" option.
Click on the "MERGE" button.

Here, you can see the new manufacturing orders shown in a tree view.
Click on that MRP order.

After that, you can see the merge chatter message of the manufacturing orders history in the chatter of the newly created manufacturing order form view.