Stepfamilies, in all their messy tangles, make inheritance complex. In the UK, 1.1mn dependent children (or 8.8 per cent) live in stepfamilies, according to the Office for National Statistics. “It has become more unusual to have that single nuclear family from the get-go,” says Sarah Paton, partner in Irwin Mitchell’s private client advisory team. “We now see cohabiting couples, later-in-life marriages and age differences.”