We just got off Mera. 2 cabins of 2, linked from initial booking. Once checked in, we were at 2 different tabled in MDR. Going straight to MDR at boarding we were given the same table. My knock on the MDR is they have way to many tables jammed into the room and it is extremely cramped.
If you buy the dining package or have a Diamond comp meal, you need to find the reservation line and book those dinners on the first day. We ate at specialty for 4 meals so MDR was less of a hassle for us.