is this incest? like is it his stepmom and stepsisters or blood related sisters?
Depends. on the version you support. The uncensored is blood related incest while the censored version is purely unrelated so fill in the blanks relationship tree.
I only support the uncensored version though so I have no clue what changes were made to the script between the two versions other than knowing that there are differences btween them to account for whether or not the cast is blood related or not.