Step parents and gifts!!!?

My partners parents split up when he was very young. His dad remarried but was always around and they have a good relationship. His mum remarried when he was 15(he is 32 now) to his now step dad. They will all be sat on the top table at the wedding and i am planning on giving gifts to mothers and fathers along with bridesmaids and groomsmen. What do i do about the step mum and step dad? Do i give them the same gifts as the other mums and dads or do they get something smaller or nothing at all?