OK, Sorry this will be long winded. I tried to get a gig at a local bar that features jazz. The guy didn't want to book me without a demo even though I've held down regular gigs in town for at least 10 years. The very next day, a drummer called me and said that a guy had cancelled at that very club and did I want to play with him that night. I did and the club owner liked my playing and said he would book me now without a demo. A week later [yesterday] the club owner called me and said a guy had cancelled for Friday [tonight] and could I put something together. I called the same guys that I played with before. Now the first time we played, we only had sax,drums and guitar.Tonight I'm adding a bass player. I just got wind that the guitar player has invited a guy we know to sit in on trumpet on MY gig without asking me. Ordinarily I might say "no" but here's the problem...the trumpet player has cancer and has been living in a hospice. He never sounded very good even at full strength and is a bit of an A hole to other musicians.Now he's really weak and I know he's gonna suck. I'm trying to sound good for the club owner because he is talking to me about a regular, once a week, gig.What do I do? At one of my previous gigs at another club, the owner told me to NEVER let that trumpet play in his establishment again because he sucks.That was BEFORE the trumpet player got sick and weak.I want to be a decent human being but I also want to establish a good relationship with this new club for the sake of me and my family.In other words, I need that regular gig.Suggestions? Thanks.