Multi Order Shipments lets one physical delivery produce one delivery note. Business Central normally posts a separate shipment document for every sales order; with this app the lines of several orders end up on the same posted shipment.
Use it to:
The field and button names below are those shown when the English language is active.
Page: Warehouse Setup → General section
Action: turn on Combine Shipments.

What happens: every warehouse shipment created from now on starts with combining switched on. The setting is only the default — each warehouse shipment carries its own Combine Shipment toggle that you can turn off for that document alone (see section 2).
Existing warehouse shipments are not touched: they keep the value they were created with.
If you never post through warehouse shipments, you can leave this off and work order by order instead (see section 3).
This is the automatic route: you pick and pack as usual, and the shipment document decides on its own that everything on it belongs together.
Page: Warehouse Shipment
Action: build the shipment as you always do — Get Source Documents… to pull in the lines of as many sales orders as the delivery covers — check that Combine Shipment is on, then post it.

In the picture, shipment SH000021 carries lines from orders 101038, 101039 and 101040, and Combine Shipment is on.
What happens: all the orders on the document are posted onto a single posted sales shipment instead of one each. Everything else — quantities, item ledger entries, the orders themselves — behaves exactly as it always has.
The app steps back and lets Business Central post normally when:
Before posting, the app checks that all the orders on the document agree on four things:
If one of them differs, posting stops with the usual "must be equal to…" message naming the field, and nothing is posted. Take the odd order off the warehouse shipment and post it on its own.
This is the manual route, order by order — useful when the goods leave with a delivery you have already posted.
Page: Sales Order → Shipping and Billing section
Action: in Append-To Shpt. No., pick the posted shipment the order should join, then post the order.

What happens: the order's lines are added to that posted shipment instead of creating a new one, and Append-To Shpt. No. is emptied automatically once the order is posted — so the field never fires twice.
The lookup only offers shipments the order can actually join: same customer, same bill-to customer, same ship-to address, same shipping number series, and the same posting date as the order. If the list is empty, one of those five is different — most often the date.
Page: Posted Sales Shipment
One document now holds the lines of every order that was combined into it.

Two things are worth knowing when you read it:
Invoicing is untouched: invoice each order the usual way, or pull the lines of the combined shipment into one invoice with Get Shipment Lines.
Transfers work the same way, and with no setting to turn on.
Page: Warehouse Shipment made only of transfer order lines
Action: post it as usual.
What happens: all the transfer orders on the document are posted onto a single posted transfer shipment. Here the app checks that the orders share:
As with sales orders, posting stops if one of them differs. Note that for transfers the combining does not depend on Combine Shipments in Warehouse Setup, and there is no field on the transfer order for choosing a shipment by hand: a warehouse shipment made only of outbound transfer lines is always combined.