Merging Tickets

When I have 2 tickets on the same order . Once the process of 1st ticket marked as ready on Kitchen entity screen and then the waitress marks as delivered the Status updates as expected to Unpaid & Delivered which is correct.

And likewise on the 2nd ticket this works as expected.

However, once I merge the 2 tickets to then provide the final bill and to settle - the status changes to New and Preparing and therefore will not close the ticket. please help smile

Many Thanks as always