Miss Manners: My friend keeps inviting herself over to my house, even when I resist

A person expresses frustration regarding a friend who repeatedly invites herself over without permission, persisting despite resistance and occasionally bringing extra guests. Separately, homeowners report a conflict between their financial satisfaction and living conditions. While they are pleased with their locked-in 30-year fixed mortgage rate, they strongly dislike their house. They feel trapped in the property, believing that moving would severely damage their current financial stability and ruin their overall economic situation.