Strange housing situation

Hello all
I have a strange situation and I'm wondering how I explain it when I get the dreaded migration notice. I own the house I live in and share with my friend (also she’s my cousin) this house was given to me by my parents about 8 years ago. My friend and I both pay a small amount ( me £25 and her £250) a month into an account my mum owns so she can take care of house insurance and various repairs, this was something that happened even before I was given the house. At no point have I ever claimed housing benefit nor have I had access to the back account we pay into.
My question is are the DWP going to see an issue with this?
Also does cousin count as living with a relative for dwp ?
Thanks