Caught in the act

My father 57 married again 4 years after my mother died of cancer, I 23 (only child) was living at home and attending the local university. My stepmother 40 had a daughter 20 were good looking and I got on very well with both of them. So much so I had started a relationship with my stepsister and as they say was caught up to my nuts inside her by her mother. Instead of the being shocked or upset she joined in having sex with and her daughter. Next week I'm marrying my stepsister as I got her pregnant and my father wasn't pleased, I had gotten her pregnant. But has come to accept what is done is done as they say. My stepmother is also pregnant now and she got pregnant by my father not me. She had tests and it confirmed I wasn't responsible as she thought as she insisted, I use protection with her every time we fucked. Something I'd hadn't always used with my stepsister. But until she says I've too I don't use protection at the moment as you can't get more pregnant when your already pregnant. My stepmother like sex and my father is a once a week or fortnight type of guy. I'm every ready type of guy and have 2 willing bed partners, my soon to be wife now shares my bed and her mother joins us when my father is away.