FLR-M evidence to establish private life outside the UK

Hi,

I am filling FLR-M visa extension for my wife.
One of the document requirement is, Evidence that it would be difficult for her to establish a private life outside the UK.

I am not getting what evidence we should be submitting for above requirement. Any advice much appreciated.
I have British citizenship. My wife is a working professional. We will be using her payslips and my cash savings to show that we meet the finance requirements. We have two school-going kids.

If you are applying on the FLR(M) form, their are questions asking you which country you would go to if you had to leave the UK and whether there are any factors that would make it difficult to establish a private life/integrate in that country. If you answered that there would be, the form would prompt you to provide evidence of this so your application would be considered under other routes, if necessary, if you did not meet the FLR(M) requirements. If you are confident you meet the requirements, you could consider changing your answer, otherwise you should probably provide evidence to support your answer to that question (languages your children speak, difficulty in integrating into a new country, etc.). It may be that a letter explaining your answer is probably sufficient evidence.

Thank you geoeng for reply to my query.