J.S.
The more you type the more confused I get. Just a little background, I am older but not old, I have two adult children, two not there yet. They are not the cleanest people on earth but not messy either, but by no means perfect. Still neither had knocked anyone up or been knocked up. I am not trying to be mean but just explain where you are not making sense to me. Your son got a girl pregnant, had no way to support her or her child, and you are talking about doing chores!
That is like saying the house burned down but I am so proud of my kids for saving the bushes out front!
Thing is if one of them had messed up, like my son, and he had asked me to take the woman in. He would have done so for the benefit of his child, my grandchild and I would have accepted for the benefit of his child, my grandchild. Sure I would have expected things from their family unit but that would have been on my son, not his family.
I am really hoping this helps you understand why so many are scratching their heads here. Your son made a child, that is his responsibility. He wants to live with his child's mom, his decision. So if you are having problems with your arrangement you need to speak to your son, not get upset with his girlfriend.