Proving tenancy

Hi,

Needed a bit of advice. 

Grandfather (Deceased) was original tenant ( old act). Tenancy passed to grandmother who expired.

Granddaughter has been living with grandmother for 2 years and at time of death.

Landlord's advocate has sent eviction notice on grounds of trespassing as relationship between Grandmother and granddaughter not given in writing to landlord.

What is the process to establish relationship as family member? Documents required?

Thank you.