This is a pretty standard partnership issue. In your scenario, nobody's at fault for anything, so nobody can sue anybody. But what if Partner 2 set fire to th

This is a pretty standard partnership issue. In your scenario, nobody's at fault for anything, so nobody can sue anybody. But what if Partner 2 set fire to the house? Then the other Partners (now including Person A but not Partner 3) could sue Partner 2 for losses. Or what if Person B, a tenant, suffered harm due to negligent maintenance of the house? Person B could sue any or all of the Partners (now including Person A but not Partner 3) for damages. And each partner would be "jointly and severally" liable for all of Person B's damages (so if Partner 5, owning a tiny portion of the partnership ended up getting sued and owing damages to Person B, they would need to sue the other partners for reimbursement). But note that Partner 3 selling his partnership interest to Person A would, in many states, trigger the dissolution of the original partnership. In this case, it doesn't matter since they never bothered to form any custom organization documents or financial allocations.