As long as all three speakers are 8-Ohms, however, do you want the ceiling speaker to be Left or Right or would you be satisfied with setting  AMP to Mono?

There are in-ceiling L/R  8 inch pairs in a bedroom, and the single sterio is on the same zone in the master bath.

If the bathroom speaker is a “single point stereo” speaker, then there are two pairs of stereo speakers as far as AMP is concerned. If all are 8-Ohms you are fine. If possible I recommend installing a speaker Volume control in both areas, but at least in the bathroom. Since the bathroom is smaller it will be louder than the bedroom. If you install speaker Volume controls, you can install “Impedance Matching” (or whatever their manufacturer calls them) controls and connect more than two pairs of 8-Ohm or even multiple pairs of 4-Ohm speakers.