block merging with blockMesh
 

Hi, I need to merge more blocks in order to model a room with inlet and outlet openings. I start with a very simplified case, just to set a preliminary case (see model.png).
I'm in doubt with mergePatchPairs and patch settings.
1. Should I define master and slave patches (see blockMesh)?
2.The inlet and outlet block faces don't match the whole face of the room block: how the wall boundary condition (and p and U values) is applied to the not-overlapped area of the bigger block?
Thanks for your help.