Basically it should not move under pressure of a shove or pull in any direction. It’s important to check your car seat instructions. Also look online for your specific car seat and how to ensure it is fitted correctly. Things to check for:
- Check there are no seat belt twists
- Double check instructions and check all seat belt routes are correct and not over any sharp edges.
- Give the car seat a shove in all directions and make sure it does not move