I just ordered a Bose S1 Pro + after reading other magicians raving about the line. After looking at the inputs again I fear it may not work well with my current headset: Samson Airline Micro. This headset’s receiver has an adapter plug I plug into my current speaker. The new speaker only has one of these ports and it is on the same controls as the Bluetooth controls. So even if it allows two inputs into that channel I won’t have any way to control the volume separately. Has anyone run into this issue?

I think I have figured it out. I ordered a XLR Male to 1/4" Female adapter.

That was going to be my suggestion

Small mixers can be plugged into a PA to allow for more channels. Denny Haney used one made by NADY for a while. It's compact with volume controls for each channel. Today, several manufacturers have compact mixers with more features.