Where under any provision of this Act it is the duty of a local housing authority to serve a document on a person who is to the knowledge of the authority—
the authority shall take reasonable steps to identify the person or persons coming within the description in that provision.
A person having an estate or interest in premises may for the purposes of any provision to which subsection (1) applies give notice to the local housing authority of his interest in the premises and they shall enter the notice in their records.
A document required or authorised by this Act to be served on a person as being a person having control of premises (however defined) may, if it is not practicable after reasonable enquiry to ascertain the name or address of that person, be served by—
Where under any provision of this Act a document is to be served on—
and more than one person comes within the description in the enactment, the document may be served on more than one of those persons.