changing setting of iMessage app for a parental control iphone remotely

My kid is travelling abroad and only has international data plan. She has emaid id setup in iMessage but no her phone number. Messages from her group to her phone number are getting undelivered. I want to add her phone number in iMessage but I dont see any option through parental control and she is unable to do as settings are greyed out. Is there any way to get the phone number added without removing the parental control option or giving the pin