My daughter lives in my second house. Do I need a landlord policy?
If you do not live there, almost certainly yes. Occupancy is what the policy describes, and a relative in residence is still somebody other than you. Carriers treat family occupancy differently from a commercial tenancy, so tell us the arrangement and we will place it correctly.
She pays very little rent. Does that matter?
For loss of rent, yes: the cover reflects the rent actually received. If the property is producing a nominal amount, that is what would be replaced after a loss. It is worth knowing that before deciding what to charge.
Do we need a lease between family?
It is not an insurance requirement and it is a good idea. A short written agreement sets out who pays for what and what happens if things change, and it makes a claim considerably simpler to settle.