Request for Landlord Reference

This is England. I own a property (mortgaged) but haven't lived there for a number of years since moving with my partner to her house. We visit occasionally. My stepdaughter still lives there with a friend.

Friend has no tenancy agreement or contract but pays £250 per month plus share of bills to stepdaughter's mum (my partner). Friend is moving out which suits me because I'm probably going to sell.

Friend has been pretty unreliable with payments but it's OK, they've been through some stuff and are nice.

Mortgage company were never informed (I like to live life on the edge).

Partner has been asked to provide a reference from a letting agent 'as the current landlord of the property' with what are, I assume, the usual questions. How long have they been a tenant, do they pay on time, would you let again etc.

In my head, but never on paper, the friend is my daughter's lodger. Money for lodging should have been paid to daughter but has been paid to my partner. Daughter doesn't pay anything (except share of bills).

The outcome I want is for friend to move out.

I want partner to say positive things on reference. How should they respond and what do they/we risk, if anything?