Registering my Wife in the apartment

Hi All,

I got the contract for 1 Zimmer house. My wife is coming to zurich for 2 months. since the contract is in may name, i need to register my wife in kries buero.
is it as staring as going to kries buero and get it registered or do i need to get the approval from the housing agnecy.
My question is in kries buero do they ask any supporting document for her stay with me.
Apartment is quite big 35m sqr which can hold 2 ppl easiley.

Awaiting reply from legends.