Re: Don't know whether to laugh or cry. Gig Hell!
As I see it, you're either in the band or you aren't. If you are, you get a fair split of the "guarantee" as well as tips. If you're not, just "sitting in," then you get what the other two choose to give you, and what you're satisfied with.
I've sat in countless times with friends, on an ad hoc basis, and never expected to get paid. But I never showed up, week after week, as a "sit-in." If you're expected to be there reliably, learn the band's repertoire, perhaps even rehearse (what a concept!), then you're more than a "sit-in."
In the end, comes down to what you're willing to take. Music can be enjoyment in and of itself; I go to lots of events where I play and don't get paid, for a variety of reasons. If I start feeling resentment, begin to consider myself "ill-used," then the gig's not fun any more, and I quit showing up. If I'm officially part of a group, I (ever the consummate pro) show up and do what I'm supposed to do. But if the arrangement seems unfair or exploitive, I figure it's time for a face-to-face sit-down and discussion of what my role is, and what's fair compensation for that role.
Seems to me that this gig's pretty "small potatoes," with a low guarantee and few tips, and probably not worth even the time we've put in discussing it -- other than there don't seem to be a lot of other opportunities available. Recommend that "honest discussion" among the three of you, and a subsequent decision on what your objectives are, and what level of "unfairness" you're willing to tolerate.
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