You wouldn’t be able to get to them during take-off and landing even if you and your child are both seated in middle seats. In fact, in case of an emergency where you needed to get to them despite the plane taking off/landing, I think you’d be better off sitting across the aisle from them rather than next to them in the middle.

If you’re particularly concerned about this, I have a slightly unorthodox suggestion. Ask the FAs if you can be seated in Y for take-off and landing, so that you can make sure you are right next to your children while buckled in. I imagine they’ll be fine with this if there is space.