Car seat buckle

My baby sister did that alot, and my brother would open the door, both while there dad was driving,
Either me or my other sister had to sit between them to keep an eye on them,
Due to this I ended up afraid to leave my kids without someone in back to keep an eye on them, usually me, as i couldn't drive back then, luckily my kids never did that,
but they did figure out stair gates, little rascals, my eldest would climb over it, but my second child figured out how to open them, I struggled opening them but she managed,
Kids can be little rascals sometimes,
Best advice i can give is go to a shop that sells carseats and ask if they have anything to attach to it to prevent that from happening, as surely now they have something for that.

i m purchasing an extra belt that goes on the chest like a bandage belt to keep my 2.5 year old in his car seat