Personally I wouldn’t put too much reliance on LFTs.
Over Christmas (3 days) our extended family group consisted of 6 adults in their 40s, 4 ditto in their 70s, and 3 children aged 6, 5, and nearly 2.
Just before getting together, every single one of us had (LF) tested negative, and all adults were triple jabbed.
By the evening of the 28th, every single one of us except the baby had tested positive, and she did a couple of days later.
Only one of the adults has had anything but very mild symptoms, but the positive tests have caused a lot of inconvenience and disappointment - booked activities needing to be cancelled, not to mention headaches over childcare for 3 children this week, since parents need to work from home while 2 were unable to go to school, and the youngest - still positive yesterday - to the childminder.
So I’d be telling her sorry, but no, OP. If she chooses not to be vaccinated, she must accept that certain things are off limits.