Not my cup of tea by any means. I did some google search and on tubes for step dad/step daughter sex to make a reply here.
I guess legally if both persons are above the age of majority and it's consensual it is not illegal. Distasteful to me yes but not illegal.
Most of these sites that have the whole "step" sex are actors I assume and not related even by marriage, but who cares, I am not going to promote it anyways.
