I spent eight years paying the mortgage, taxes and repairs on my parents' house, assuming that when they died, my sister and I would share both the grief and the responsibility. Instead, I now co-own a property with a sibling who refuses to move out, pay rent or agree on a plan, and the family home that once felt like a refuge has become a legal and emotional minefield. My situation is personal, but the dynamics are increasingly common as adult children inherit homes together and discover that shared ownership is far more complicated than it looked on paper. In...