How can I read only the new Id that i want ?

I am doing a ticket form and I have session for this.. Session = 0 when ticket is in compilation and session=1 when ticket is open..Now I add some people when session is 0 and send their a message, now i want that when i forget to add one people  and session goes 1 to send the message only at the new ones not at the people i add before..
'If Session("IDStatusTicket") = 1
"here i want to read only the ID of new people that i add not before 

Thank u :)