New to this topic - Can they really be sure?

[thedinosaur]

Sorry I'm not sure if this is the right topic.
I'm in a relationship with someone who's sibling has Bipolar Disorder.

We have been talking about TTC recently which has made me think about our general future a lot more.

The sibling still lives with DPs parents (sibling is in her 30s).
She functions well most of the time, works, socialises. Can't really drink or go out too much because if she doesn't keep herself in a routine and gets enough sleep she gets down and depressed.
Every year or so she gets "ill" (not sure if this is the right word to use), it can last weeks in which she goes between down and depressed to "manic" - it involves being very nasty verbally, intimidating and paranoid (thinks people talk about her etc). She's sometimes up at night thinking there's intruders in the house, knocks on people's doors and wakes them, she's threatened a family member with a knife years ago and destroyed property.
DPs parents getting older and finding it harder everytime she's unwell.

They thought it was a bit more controlled everytime but a last time she turned ill it lasted over 4months - the last time it lasted that long was about 10years ago.
When that happens she does not work, has to be monitored 24/7 and can't really go anywhere on her own.

I've spoken to my DP about her condition as I am aware we might have to be a lot more involved in caring for her in the years to come. I asked him if there's a chance she can be violent, I am really inexperienced in MH issues so this might sound like a silly assumption but I wanted to put it out there especially since there will be kids involved in the future.
He said definitely no, he said it's all about intimidation to her. I've experienced this a little, she can stalk people around the house, get in your face, call you names, try and broach subjects that put you on edge, she will walk around with random objects that could hurt you like a thick stick, knife etc and it is intimidating.
My question is - how can he be so sure she won't ever be violent?
I know she has punched him before (not in the face and not particularly hard but still), she ripped jewellery off a family members body, she has pushed and shoved people, she has thrown a glass at someone and threatened someone with a knife.

He maintains its all about the "threat" - but can he be 100% the threat will never turn into an action?

Again, I don't know enough about this condition and I am really sorry if this is a silly concern or a sensitive matter. It's not going to change mine and DPs relationship, I'm in it for the long run. I just want to learn more about it and prepare myself for what I might expect in the future.

In general people who have serious mental illness are more likely to hurt themIt's than other people. It's actually very rare for someone with mental illness to be violent and statistically violent crimes are much more likely to be commited by people without a mental illness. That doesn't mean that it doesn't happen though, normally when the unwell person is terrified and in a fight or flight situation (in their own mind anyway). The best predictor is previous behaviour and your DP and his parents obviously know her best.

When DH is poorly he is generally terrified and can become very aggitated and agressive, less so with me than with strangers. What is your relationship with her? She is a person rather than a condition and by building a good relationship with her in general will help if you are ever involved in supporting her when she is unwell later. She will also be the best person to tell you how you can best help and support her if she becomes ill in the future as she will know what works for her.

Being around someone when they are very poorly can be distressing and scary enough for adults but even more so for kids, so it's not just the physical threat to consider. I love DH and I trust him but there are times when he has been unwell that neither of us would want our kids to witness. Theres also a big difference between me taking a calculated risk myself and taking one with a child, theres no way I would take a child into some of the situations I have gone into.