Previous background on SIL1
here - she's in her mid-forties and acts like an irresponsible teenager most of the time. She finally got a divorce from The Convict (the last time he got out of prison, he moved in with his new girlfriend, which was the last straw SIL needed to actually file the paperwork), started da
ting a 20-year-old meth addict, dumped said meth addict, then moved into a new house. (Still one of the IL's rental properties, but a smaller one.) She's been theoretically supposed to pay rent this whole time, but never manages to pay more than $50 if anything, and even that is rare. MIL told her this time, though, that the house was for her and her alone. She had her sign a rental agreement and everything, saying that taking on other tenants without landlord approval (i.e. my ILs) was grounds for eviction.
Meth addict boyfriend calls up MIL to let her know that The Convict was skulking around SIL's new place. MIL asks SIL, who denies it. MIL says if she catches The Convict living there, SIL is getting evicted for real this time and she's on her own. SIL swears up and down The Convict hasn't moved back in with her. It doesn't occur to SIL that since her new place is half a duplex, her upstairs neighbor also knows MIL and might call her if SIL turns out to be lying

Not unexpectedly, SIL moved The Convict in with her. MIL finds out through the upstairs neighbor and tells SIL she has to get out or she'll be formally evicted. Here's the brain-hurty part:
1) SIL and The Convict are in love again. For real this time!
2) They found a new place together. SIL has a decent job (not great, but decent), so theoretically she has money, but she spends it all on stupid things. She could barely scrape together $25-$50 a month for rent (instead of the $350/month she owed). Their new place is in one of those extended-stay hotels for $220
a week. How on earth are they going to afford $900/month when they couldn't afford $50?
3) Oh, but it's different now! SIL sold her car because the new place is nearer her work so she can walk. And there are all sorts of fast food places nearby, so The Convict can get a job at one of those!
4) (The Convict has not actually held a real job - with the exception of selling weed - since she married him four years ago. He'll get hired and then quit a week later because someone was mean to him, or they didn't like him not showing up for work, or showing up for work high. I highly doubt he'll actually condescend to do any real work.)
5) SIL wants MIL to pay for her and The Convict to have
another wedding. Because this time it's going to work for sure!
I'm hearing all this second-hand from MIL because DH and I are trying to stay far, far away from this mess (and make ourselves as small a financial mooching target as we can). I'm kind of morbidly curious to see how long their "Livin' on a Prayer" phase is going to last this time!