A private fostering arrangement is an informal arrangement made by parents, for a child (up to the age of 16, or 18 if the child is disabled) who is not a 'looked after child', to be cared for by people who are not immediate family members, for a period of more than 28 days.
An immediate family member is defined in the 1989 Children Act as a ‘grandparent, brother, sister, uncle or aunt (whether full blood or half blood or by marriage or civil partnership) or step-parent'.