Changing tree so stepson isn't listed as son?

Need help on my tree (Kerry Friedman Rosen). I am married to Philip Terry Rosen. His son is Philip Terry Mason II. My first husband was Kim Herzinger and my two daughters , Jessica and Caitlin, are from that marriage. They are PTR II's stepsisters, not his half-sisters. Have been trying to fix this but can't figure out how to! SOS! Thank you. --Kerry