Create New Session Based On Accounting Update

Hi, I am trying to create a new session and insert it into radacct table based on an accounting request from NAS. When NAS sends Interim Update I want to check if that user already in radacct table and null or not null. If not null then create a new session and make that user online in freeradius. I am not sure if it's possible or even the right thing to do. Want to do that because sometimes user online in NAS but offline in freeradius. Thank you