Hi Rivergal , we had 5 teenage daughters at home at one point,and i remember well the issues!

I would not allow her to stay over at her new boyfriends house, have you met him yourselves?

To avoid coming out with a straight no! suggest you meet him, and get him to come over to your house for a meal or something, and you get to know him better for your peace of mind.

At 16 they do think they know it all, but we still have a duty to protect them too.

Is this the first time she wants to stay at a boyfrieds. At least she did ask. Say no but explain why, dont fall for any stories like "well all my friends can stay with their boyfriends"

it not easy saying no, but be strong.