Common law - proof of joint residence

[Alistair]

Hello, I have a question, how can we prove that we are living together if the house we're living in belongs to the father of my girlfriend? We already have a joint bank account, and we are planning on doing joint purchases for the house. What else can I add as evidence?

Thanks for the help.

[RobsLuv]

Have her father draw up a simple rental or lease agreement that names both of you as occupants.