I would like to have an additional lock on the inside of a multi-point locking uPVC door at a height out of child's reach for safety.
We have the usual key lock on both sides beneath the handle, but our son is a master escape artist who will take advantage of any unlocked door or misplaced key.
It won't work to have a thumb turn instead of a key internally, because that'd just be an easier challenge. We need an additional lock on the door our of the wee man's reach.
I've searched online but can't find anything referencing an additional lock on a multi-point system. Is it possible to do, or are there any alternatives that can be recommended?