I have pictures of all the other issues (gaps in the door frame to the outside, crumbling linoleum floor in the kitchen, Gas Company service tech advice re: a potentially explosive gas heater, spider bite marks on my arm - all things that fall under California Civil Code 1942), except for the...
ndragon is right, see what your lease says about additional tenants. My lease states that I could be subject to eviction if guest stay over a month. So you could threaten that if she doesn't sign the consent form then you'll instigate an eviction per the lease.
My jurisdiction is: Los Angeles, CA
I'll try to be clear and concise with this... my former landlord failed to remedy (after 60 days of a written notice) multiple repair issues and insect infestation issues that per California law violate the Implied Warranty of Habitability and Health Code...