[Zope] is it possible to upgrade from 2.9 to 2.13?

[resending as original seems to have got lost] I got stuck with 2.9.9 because 2.10 introduced a major leakage in the ZSQL Methods. Now the number of users in my web site have increased and other leakages have become also major issue (e.g., PageTemplates.Expressions.SubPathExpr). I was considering a major upgrade to 2.12 or 2.13 and I was trying 2.13.8. However, how can I install products?? It states in 2.12 "What's new" that they are still working but in fact merely dropping Products in the site-packages does not add a product. Regards, Fernando