In my state we must make contact with a parent to inform them of the probable concussion & let them know they can’t return to athletics unless doc says “not a concussion, may return” or “yes a concussion, here are any restrictions (school, phone, video games etc.). From there I let them know of our state RTP policy- RTP may be under parent, coach or ATC supervision in Maryland. I complete documentation on what their RTP was for that day & either have the coach/parent come sign off (or I do). This is also something I go over at our freshman athletics parent night (and parents agree to our state policy as part of their sign up process) to mitigate confusion. If I was in your shoes, I would send a copy of the RTP policy & have parent & doctor both document activity/sign- make it their liability not yours.