I'm an active local musician/electric bass player and I have a group of musicians I call in 1st, 2nd, and 3rd order for gigs. I have a drummer who is first call. I bring him a lot of gigs, judging by the size of his 1099 at the end of the year.
Anyway, he called me a while ago asking if I would mind if for a couple gigs at a restaurant not far from him, if he could use our piano player (2nd call guy) and a string bass player for the gig. His reason for this was the owner "wants string bass" and I'm an electric player. I said fine, but indicated that if I was going to call him first for all the gigs I have, I'm expecting to be part of the gigs if the instrumentation is the same (piano, bass, drums) that he books.
Personally, it irks me when I bring musicians a lot of work, find the musicians, arrange the rehearsals, get everyone music, and then they go off on their own, when there are no apparent interpersonal skill or other problems. I also think the owners' string bass requirement was hokus.
I later see all over the Internet that he has named the trio, and gotten a professional video done. He is listed as the contact for this group, and they are doing music festivals around town.
How would you proceed with this case?
You don't play double bass. He owes you nothing.
Play double bass, get reciprocal calls for gigs.
If you pay the guy on a 1099 then he's just a contractor to you anyway. He owes you nothing. Get over yourself.
I bet if you gave all your clients the choice of upright at no extra cost they would jump at it.