Arcade site registration modification

I need someone familiar with modifying phparcadescript 3.0. I need a modification done to the registration process. Right now, it collects an email address from the user without checking to see if the user is 13 or over. I need it to first ask the user's birthdate, and: - if the user is at least 13, proceed with the registration as normal, and when the user is added, include the entered birthdate - if the user is under 13, a warning is displayed and a link given for a parent to fill out and mail or email to me giving permission for their child to use the site. This is to be in compliance with COPPA. Hopefully, someone will have experience with modifying phparcadescript 3.0 for COPPA. Thanks!