Chatty parent makes late closure

[Snowmom]

Do I make parents responsible for their child when they are present? Absolutely yes!

I would write up an addendum that would need to be signed and returned stating:

Subject: Closing Time

Effective immediately, a $1 per minute late fee will apply to any families still present after my 5pm closing time.
I am happy to touch base with you if you feel the need to discuss any issues pertaining to your child's care, but it must be done within the hours of Xam-Xpm. Please allow yourself adequate time upon arrival to gather your child, their belongings and any information you need before departing before 5pm.
Also, I'd like to reiterate that when you are on premises, you as the parent are responsible for your child's behavior and any disciplining that may be needed. For the safety of others, please do not allow your child to break house rules or run off unattended and unsupervised.

Signed,
Provider

I wouldn't have any qualms about telling a parent they need to tell their child to listen to the rules or put their child in a timeout. I'd also be scooting them out the door (physically- by arm on shoulder and opening the door for them).