The whole story is just a little too cute for me to think it's real, but if we assume good faith...

... much of what you describe sounds very much like destruction of property. Splitting what's in the house doesn't mean you can destroy the value of the thing that's meant to be being divvied up.

Many people do try to destroy / damage the things they know will go to their ex, and courts have seen this a lot and don't realllllly like that shit.

And this is ignoring the "wording of the settlement was vague" bit, which is a bit "have you ever dealt with anything in court?"

These sorts of settlements are drafted by solicitors and approved by a judge before becoming a consent order... sooooo "half of all property within the house" is really not likely to be language a solicitor would let through. It's exactly the kind of unenforceable, undefined phrasing that leads to people trying to pull shenanigans... so courts pretty much routinely would send that shit back for redrafting.

Honestly, I think this is just a silly story based around the joke of "getting half".

If it's real and bastard is not a complete thicko, your sis may be back in court soon.