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

[Fernando Martins]

[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