MB4 236a: Dwellers in Apartments and Hotels Obligating Towards an Eruv (370:3 - part 2)

Does everyone have to participate in an eruv chatzerot if they are in a partitioned room where each section has its own entrance to the chatzer?

If the mechitzot don't reach the ceiling it's viewed as one dwelling.

What if some of the residents erected partitions that extend to the ceiling and some didn't?