Do employees of a school have to park in the school parking lots or can they park on residential streets even though there’s plenty of space?

A bunch of teacher’s aides are parking on our residential street, instead of using the school parking lot that has plenty of spaces. They are making it hard for residents to pull in and out of their driveways and are impeding traffic flow since the street isn’t wide. There’s no reason they need to park on our street. Wondering if there’s a set bylaw that school employees need to park in their designated lot, maybe for liability reasons. Thank you.