If there is a syndicate/group agreement, it should cover the eventualities in there. If there is no agreement, or there is but it is deficient in this respect, you could try to use their desire to get you in as justification to adopt a suitable clause with effect from the point of you entering into it.
There are probably some model agreements about, or actual ones that you could use or suggest, as a basis for the group in question.
I have one for gliding (which is not that much different, but may not cover in some respects things like engine funds). Feel free to email me if you want the text to have a look at.
Chris N.