Retirement post Brexit to Switzerland

Hello,

I am looking for some advice for my mother in law who wants to retire to the Vaud - she's currently living in the UK.

I am aware that there are 3 requirements for non EU retirement and that its at the discretion, I'm wondering if anyone has any experience/reflections, particularly on:

1. How much income qualifies as enough to live on

2. Likelihood of a decision in her favour

For some context on her: she held a C permit in the Vaud from roughly 1990 until 2014 when she gave it up and moved to the UK to look after her own mother. She still owns - currently let out - the family home in the Vaud. In the interim period, with the exception of the pandemic years she has visited Switzerland for holidays/to see friends. The income from the property is her only income i.e. she will not be seeking a job. She speaks French fluently. She has a UK passport.

For some context on my/my partner's situation: My partner had a C permit from 1991 to 2014 when she moved to London for a job. She was born in Switzerland but didn't apply for a passport. She has returned on a CDL (working for an IO) and her 1st language is French. I have a B permit and work for a Swiss company.

She might want to call her former commune and ask for their advice.

So what is she planning to do? Live in the family home and have no income from it or continue to rent it out and then rent somewhere else for herself?

Is she retirement age or younger? If retirement age then she should have some sort of pension from one of the countries I would guess. Did she work here or did her husband?