How to Convert Individual account to Household via the Web?

When our web patrons purchase education tickets via the web they can add new registrants, which are created using Local Procedures.  We have modified this process for V11 and it is working.  The piece that we're stuck on is if someone that has an Individual account wants to add a registrant the account must first be converted to a Household prior to adding the new registrant as an affiliate. 

Is there a local procedure that get called when the Household Conversion process runs? 

Does anyone know the name of the procedure that is executed when the Network's Household Conversion process runs?

Any help would be appreciated.  Thanks!