2D Tilemap room prefabs for dungeon generation.

Hi,

I'm trying to make a rougelike dungeon generation where I have a series of prefabs with room layouts and door 'slots'.

I am trying to have a scene with a grid which loads in various room prefabs and connects them by their door slots but having difficulty finding out how I can join the tilesets from each room onto one tilemap in the scene.

E.g each room has 4 tilemaps, I don't want a dungeon with 10 rooms to have 40 tilemaps on the grid - just 4.

Thanks.