Yeah you can get all four but if your really good there are more to be had. The next installment is due in December if I read correctly in a post but it will be the last for now as the author would like to broaden their scope a bit.
https://workupload.com/file/Yggm42dQ
This should get you through the game though I prefer seeking it out myself.
I have accomplished the harem before, resulting in a five some with all the sisters and mother but this playthrough I was attempting the same thing without any pregnancies, I wanted to see how mrs steel reacted if she wasnt curious about any other the girl's mysterious pregnancies. However, this time I made a mistake and cant figure out why, bella forces me to break up with her or Rachel after Rachel catches us and I know there is a third option but dont remember how I got it last time.
I am confused why that walkthrough didnt go past day 30, it got right to what I needed and stopped.