Maybe we need a different approach. Consider:
1. Aircraft are not automobiles.
2. There are other ways, besides the automobile CRS, to provide good protection against injury in an aircraft crash or turbulence.
3. A mandate that all occupants be restrained in an aircraft need not mandate the use of automobile CRS.
4. If we do mandate that all occupants be restrained in an aircraft, we should continue to allow parents to use their CRS.
5. Then, if they bring the CRS, they can be seated wherever the CRS is allowed.