[Zope] Postponing insertion in database

Hi, my problem is that i have three consecutive forms: when i click the submit button of the first one, i insert in the database and then redirect to the second form, and the same with the second and third. But the three insertions must be completed if i want to have a database not corrupted. If the user stops in the second form, for example by closing the navigator, the previous insertion must be undone. I thought two solutions, the first one is using hidden inputs and insert all in the last step, but i don´t like very much this solution. The other one is using transactions, but i don't know how to manage them. Anyone could help me with a suggestion or a link? Zope 2.4.2 ZPsycopgDA 1.0 PostgreSQL 7.1.3 Thanks. Bye. Juan