School time setup in apple watch

I know you can setup school time of your kids apple watch if the watch has Cellular and created as a family member watch. But my kid has her own iphone and apple watch without cellular and I want to define schooltime in her watch and looks like theres no way :( Please let me know if theres an alternative way to restrict use of apple watch during school time.

As mentioned, I tried to setup her watch via Family Member but since watch doesn’t have cellular, I couldn’t continue that option

Thank you