Converting attic to master suite

We have what our realtor calls an "attic rambler," with a full staircase to a previously unfinished attic space. The last owners finished this space to include living room, bathroom, and a bedroom at each end. The bedrooms at each end have full windows. The rest of the space has skylights.

I'd like to convert half of this space into a master suite, with the living room space being the bedroom portion, and one of the current bedrooms becoming the grand master bath. So the only egress window would be in the bathroom. Can we do this?

If we left a large opening between rooms, and didn't have a door, would this satisfy the codes/laws? Just have the bedroom open to the big bathroom?