I am an electric-only, jazz bass player. Some of you know I have evolved into what I call a contractor's model of band management. I started three bands and work with 11 musicians. I have first call players in every position, and subs about 2 deep for when the first call guys are not available. I've been pretty busy as a result - as I let the second call musicians perform at all gigs they book, and with a wide variety of jazz styles and instruments to offer clients, I seem to be able to get a lot of gigs. I also make a point of bringing on people who have sales backgrounds, even if they aren't top players, training them in jazz, and then enjoying their phone calls asking me which group they should pitch for the various leads they have generated. There's another bass player I met a while ago, and he plays upright bass, cello and electric bass. We did a musical festival and were on the program at different times. I think he's at least as competent as I am (probably even better) and he keeps offering to play duets and other things. I think he sees how busy I am with gigs, friends me on facebook, and calls me now and then. He invites me out to his gigs and is active commenting on my facebook posts regarding music. He's the only fellow bass player that has ever done this. It's always been cats on other instruments trying to build a relationship that do this. So, this is new to me. Then, the first call drummer I work with, who is in sales, indicated he found a gig but the client wants upright bass -- would I mind if he used the keyboard player in the jazz trio I formed and the three of them (the upright player who contacts me a lot, the keyboardist, and this gig-booking drummer). And then, after I posted a trio gig the other day, this bassist asks if he can sit in with the group on facebook. I would like to ask: a) What would you say to the drummers' request to do the jazz trio gig without me due to this client request for an upright bass (which I don't play)? [Incidentally, I have never had a client insist on upright bass in the last 110 gigs I have done]. [Also, this gig booking drummer just called me with three other leads for our trio, without the upright bass requirement as well, so I don't think this is an attempt to necessarily displace me from the jazz trio I started, particularly given how busy I've kept this drummer with my own sales efforts]. b) What would you say to this upright bassist's request to sit in with the jazz trio group, essentially, taking the bass chair for a few songs? Just curious what you think. I have already responded to (a), but am thinking about (b). But I would like to know what everyone thinks before the big reveal on (a ).