Panda39,
Yes they are still married.
Some of the property is in Dad's name and some of it is in both of theirs, and some of it was paid for by me and my siblings, meanwhile there is also family business involved. So it's not a simple divorce case to be sure.
Yes, good question. It is possible to buy her out of her share but she did not accept our offer, at least not yet.
Our growing up was very stable, most of the BPD symptoms (we called them fits) happened behind closed doors. I am pretty sure alot of the mother daughter bond was missing - realizing how we were never that close - I don't know..still processing that part.
I think the split happened because we didn't catch it early, didn't know about BPD. By the time we learned about it us kids we're grown up.
Psychology was always a topic you stay away from, but now I think this is preparing me to help someone somehow in the future - if only because I know this kind of thing can happen.
The two who believed all her explanations and denials did not have a good relationship with dad. Go figure

Dad is a strong authority figure compared to 'normal' standards. I have alot of respect of respect for him. So do the other two siblings. We operate as a team.