Hi!
It sounds to me like you want to auto generate a unique ID for a new form and you want it to be sequential?
This is a pretty common question, if you search the forums you should find a number of threads on this.
For example here is one good thread that discusses several different ways of doing this including querying SharePoint for the SharePoint ID of the form thta was just created:
http://www.infopathdev.com/forums/p/2197/19614.aspx#19614
Good luck
Ted