Student living in parents 2nd Home

Tenancy Types and Management

Our daughter who is a student is living in this property, we wish to rent out the second bedroom to another student.

We wish to get advice on the following:-

1. WHat legal relationship if any should we have with our daughter.
2. Can our daughter have a 2nd occupant under a 'lodgers agreement' - this gives her flexibility.
3. Should we simply take the second occupant under an assured leasehold (room)

In the absence of a leaseholders agreement with our daughter is she the landlord in residence by default because she is a family member?

We have a mortgage and out goings so would expect to pay tax on the rental after deducting 50% of the expenses.