UK Landlord Forum / Life

We have a tenant that has left the family home & his  wife & kids. The wife is not on the Tenancy Agreement. We have served notice & this expires in May. The council have refused to help  her  with housing  if & when she has  to move because she is not the official tenant. She has asked us to write her a letter stating that she has been living in the property with her children for the last 7 years so she can present this to the council in the hope she will get help ?

If we do this lady a favor & write this letter-  will it Jeopardize our chances of getting Possession of our property  or cause complications at court?

Appreciate any advice