(GDPDGPR will probably raise it's ugly head ... )
I think it's OK if one person controls the list, names have consented in full to the purpose for which the list is kept (and can freely opt out), and you can avoid sending bulk mailings with everyone's details.
Or, keeping it simple, why don't organisers in need of help advertise what they need and where etc and see who puts their hand up? I suspect it will mostly be the same people who enjoy the comradeship of helping out (I can highly recommend it) but if we can show potential newbies how to dip a toe in that might be appreciated.