Do not assume the unmarried relative has the most available time.

Households with children get treated as legitimately busy, and everybody else gets treated as available. The unmarried brother, the childless cousin, the one living alone: they are asked to travel at Christmas, to sit with the relative, to take the awkward shift, because their commitments are less visible. Invisible is not the same as absent. Their work, friendships, health and quiet are real claims on their hours.

Ask what somebody’s week actually looks like before assuming there is room in it. Share the family jobs by conversation rather than by who seems least encumbered.