ILR set M question

I was due to apply for my wife's ILR set m tomorrow..She arrived on a Spouse visa on 9th March 2015.
Her FLR was granted on 30 Sept 2018..and her BRP card expires on April 28 th 2020.

Sadly her daughter died yesterday in Thailand in a tragic accident and she flew home to sort out her funeral and settle all her financial affairs.She is due back on 20th March..So if I submit her ILR application soon after and pay for it but do not get an appointment until after her BRP card expires what is the legal position..?

Again is she alright to pay for ILR two weeks or so after she has been in the UK 5 years..ie after March 9th..and before her BRP card expires..

Can I submit the application form and pay for it now and then arrange for the interview and biometrics later when she has returned to the UK>

Apply when she returns.

Date of application is the date you submit and pay online. Date of biometrics is irrelevant and can be after visa expiry.

She can apply at any time, if in the UK,before her visa expires.