Illana was telling me about a huge split in her Harry Potty Fiction Writers' community. An issue (sorry, no details) arose that divided the community in two. It was untenable. It tore her community apart.
Half the community left.
If you have one community, the cost of replicating the infrastructure to create another identical community is minimal. If you have a big split, use the same community software to create an identical community for one group to join. Give them a new home. Let them customise the looks and name if they like.
It’s a mutually satisfying solution. Far better than losing half the group. You will probably find one group dries out and the community gradually reunites.
If members want to leave, show them the door to their new home.