There is no such thing in law as a "custodian of rights". She is of the age of consent.
Obviously, you are having trouble coping with your desire to boink her, so I'll use smaller words.
She is not an adult.
You are her father. This means that legally, she is still your responsibility until she is 18.
This means, that adovacting, that means "sticking up for", her Rights is your responsibility.
This also means that legally, you can be held criminally responsible for the consequences of her actions.
Yes, she is old enough to engage in sex. But, you are her legal guardian until she is 18. This would be like an Army Sargent ordering a Private to blow him. Bad mojo.
Got it? Or do we just have to assume you are completely mentally deficient?