Phone/fax sharing a line

Yes but you should set your rings differently so you can answer your phone

Unless you fax a lot I wouldn’t bother and just hook it up when you need to fax something or if you do fax a lot, get a second separate featureless phone number.
Xfinity sets your phone rings
Brother sets your fax rings
Then you have to worry about the fax answering on a regular phone call and never getting to your voicemail