"Join in" doesn't seriously fit in any of your respective examples. The truth is, I am not sure "be a part of" by itself functions one example is 3 both. Stack Exchange network is made up of 183 Q&A communities which include Stack Overflow, the biggest, most trusted online community https://donovanijgbv.mybuzzblog.com/16478575/detailed-notes-on-567tv-live-show-benefits