I think the functionality needs to be separately developed.

You mean something like "Resteem to blog" and "Resteem to community"? The issue with this is probably not all members should be allowed to resteem to the community or the community feed may be filled with resteems.

One thing i didn't try is to resteem from an hive account "hive-xxxx" but i suppose that's just another account with hive name on it.

No, "hive-xxxxxx" accounts are not just simple accounts. They are the OWNER accounts of the communities.

That's why I said resteeming from it should work to resteem to the entire community, but I doubt this is a long term solution, as this account is not meant to be used to post/resteem/vote.

Right now I can't test any further. It looks like access has been password protected again on the beta site.