Rights when in a relationship but not married/living together

yes, sounds like for him it is a friends with benefits situation.
for her it is an exclusive devoted relationship.
but unless he takes out power of attorney and makes her responsible for health matters if he is incapacitated, which is v unlikely he would, she has no official standing.
she really needs to look after herself.
i doubt that challenging her on this directly will help.
just be a supportive influence.

Everyone is so right - the children are his next of kin and will inherit if he dies, unless he makes a will in her favour. They would be entitled to make the funeral arrangements. Sadly she has no legal standing at all. I hope she will keep her own property and not invest any money in the relationship. He sounds very selfish and I expect is perfect happy to have her look after him, but refuses to give her financial security. A real charmer.

@GagaJo I am glad you said that, thank you. The problem is my sister will never back off or not get involved, she is totally smitten with him and would do anything for him.

Your sister needs to stop putting so much of herself into the relationship. Give only as much as she gets (and I'm not talking financially/materially here).

@JaneJudge the issue if he is ill is the main thing. When he was so poorly last year she was with him when she collapsed so she was involved from the start. His children do not live near and they were unaware he was in hospital until he was much better, several weeks later. My sister's worry is that if they do start to get involved with their father again - perhaps as his condition worsens the children will swoop in and take over.

Been there. My bloke's children did everything they could to get rid of me. I backed right off and now he is older, lonely and sees those children rarely. I feel sorry for him, but am not getting involved (other than a superficial, part-time relationship) again. He should have taken a stand years ago, didn't, and therefore will have to bear the consequences.

Silly old men. They should appreciate a good thing when they see it.

@Grandmabatty no he won't, I believe his divorce from his ex wife was acrimonious, and he feels like he gave up a lot. My sister is quite wary of bringing up the subject now.

No rights whatsoever. At best, she is a kind friend, and rights, moral or legal, don't come into it ☹

I understand regarding the children notifying her if he is ill etc but your sister and her partner presumably both live in their own properties so have autonomy over their own financial affairs, which is how it should be.

I feel for your sister and can see how her long held values and thoughts have taken this route, but to be honest I think this man has been quite open and honest.
My uncle has a lady friend who values her independence, so the other way round from your friend. I quite respect her for it. She is a divorcee too and it seems that marriage was not a great state for her. They have also supported each other through stuff. But that doesn’t really mean that they need to own each other’s assets.
I hope that she can continue to enjoy their relationship.

She has no rights whatsoever and would be advised not to move in with him, not to offer care and not to spend money on him. His children will have the final say on anything. Would he consider a civil partnership?