evidence of cohabitation

[luqmanzaheer]

Dear Zimba and senior members;
I am going for ILR under Tire 1 ent in set(o) form page 75 demands evidence of cohabitation for up to 2 years. and guidance is silent on the points below
1. what kind of documents are acceptable as evidence of cohabitation
2. is only one letter from GP says both of xyz are living on xyz address is acceptable as proof?
3. some members of this firm says for this section applicants need evidence from 6 different sources for 2 years is this true? if true then where it says in immigration rules?

please members help me to sort this problem because very less time left.