To not want to invite H2B's father's partner's daughter to wedding

[flowersinspring1]

AIBU to not want to invite husband to be's father's partner's daughter to our wedding which is abroad?

H2B's father and his partner have been together 5 years, not married and don't live together. His partner lives with her daughter.

The daughter is in her 30s and has a mild disability. This is not immediately obvious if you speak to her and she can be left alone for long periods of time (i.e. when the father and his partner go on holidays) and she does have a boyfriend of 3 years.

The clincher is whenever there are family get-togethers his father's partner always brings her daughter along. I think this is for social support as she has never felt accepted by the family. There has been a lot of coercive control and manipulative behaviour, which I suspect is the reason for her feeling that way.

Neither me nor my H2B are close to his father's partner or her daughter but of course the partner will be invited. However we don't want to invite the daughter.

AIBU?

It's not the OP's dad, but her future husband's.

Perfectly fine not to invite her.

Thing is, it seems from the tone of your OP that your don't want her there because of her disability. You go into a lot of detail about it. Also, you don't HAVE to find her a seat, a room, food for God's sake, you just allocate them.

I think if you got on well with her, she was super fun, and added to the dynamics of the party, you wouldn't think twice.

Her awful mother really is a red herring.

YANBU not to invite her, but don't fool yourself about why.

You don’t have to invite her, my fiancée isn’t inviting her dad’s fiancée’s adult children to our wedding abroad either. They all have partners and kids so three invites turns into 8 and we have practically no relationship with them, so can’t justify the cost of 8 people we barely know and don’t really speak to.

Disabled [especially adult] offspring are a very rich source of 'AIBU' material - if we were e.g. talking about someone with a serious disability, who frequently found herself socially excluded, etc. I might be tempted to invite her, both as gesture of appeasement towards the future FIL & as a general piece of compassion. If she's almost entirely OK then I'd be quite comfortable [with impeccable politeness] telling the FIL to poke it.

@iborgia it’s really not that and I’m sad if that’s how it’s come across as I have a disability myself. I included that information and I thought it could be relevant, given she needs extra support in life. If people feel it isn’t relevant then that is fine. I would feel the same way if the partner wanted any of her children to attend.