Speaking from experience, in our case, having a new-born grandson and his mom in our house was something we invited and enjoyed, up to a point.

There came a time when my daughter and I were not getting along well at all and we all knew she had to move into a place of her own, even though I was loathe loath to let the baby go by then. She did not shirk from work, but was determined not to move into sub-standard housing, so we remortgaged our house, took the equity and bought a house down the street for her with a written agreement that she buy it from us within two years, I think it was. She did, paying us back for the original downpayment, and it worked out, okay, except that Rog regrets we have higher house payments and nothing to show for it, in our own place. (Because of the housing market at the time, she wound up with about $40,000 equity from the getgo which he wishes we would have insisted on getting a portion of.) He would have preferred adding on to our place and upgrading some things which really need upgrading, but I still don't think that would have worked between my dau. and I...we're too much alike.:-)

So, your best solution might be to buy them an RV, if you can swing it, and send them on their way!