Case. The son and his wife moved in with the parents “while saving for a mortgage”. A year on, the mother cooks for four, the father says nothing about money, and the couple cannot recall being home alone.
Model. Adult nodes joined an adult system with no contract: boundaries, terms and contribution unspecified. Parent–child roles restarted on top of adult–adult ones.
What helped. A family council with a move-out date, a share of expenses and the rule “two evenings the kitchen is ours”. One awkward talk proved shorter than a year of silence.
Lesson. Helping adult children works only under a contract: terms, contribution, boundaries. Otherwise it becomes a quiet lease on your marriage.