An admin adds people from Settings, under Household. Adults get an invitation link. Children and other dependants can be added without a sign-in.
An invitation link is shown once, when it is made, and works for seven days. It only works for the email address it was sent to, once that address is confirmed, and only once. An admin can cancel a link that hasn't been used. Someone who joins gets a household role. Their own budget stays private until they share something.
A household holds up to six people with their own sign-in. Family members without one don't count toward that.
A family member without a sign-in can have a full budget of their own: income, bills, spending limits, accounts and goals. The person who creates it becomes its manager, and can add other managers. A family member can also be listed with no budget at all.
When that family member is old enough for their own sign-in, an admin who manages their budget can send them a claim link. Before accepting, they see the budget and its current managers. They choose which managers stay. The budget keeps its history and becomes theirs. Keel never matches people by name, so a budget only moves through that link.
The budget leaves the household when it moves, so contribution terms other people had into it end, and past payments stay on record. If the family member already joined with their own sign-in, everything the household recorded for them moves to that profile. If both profiles had contribution terms for the same budget in the same currency, their own terms keep going and the family member's end, unless the family member's were the only ones still running.