Converting Vacation Worlds To Livable Worlds Y/N?

I use a mod that makes my Destination Worlds livable, only because I've been playing one save for 27 Generations now and with all the kids, their kids, townies etc, there is a housing crisis, so I needed more land.
But even that unfortunately is not enough to help. There are 12 Sims, pretty much living in one household, even the 20x15 lots. :'(
Even making the birth rate 1% for the last 2 generations hasn't really helped. And the faster I cull the random townies, the quicker they spawn back.