Sometimes they're part of an estate divided up among multiple heirs, whose relationship is mediated by a will and a probate court. Title can be contested through a divorce, where disputes are settled by a divorce court. At the outer edge of complexity, you get things like polycules or lifelong roommates who've formed an LLC s they can own a house among several parties, but the LLC will have bylaws, and typically all those co-owners will be fully engaged in any sale process.
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