I use the following method:

1) Log all changes. (I use IBExpert for that)

2) All scripts are distributed with the application, (I use another FB database)

4) My DB has a field with a DB version number

5) On application startup, before opening any tables it checks the version against the latest version of the updates scripts and run the scripts required to bring the DB up to date.

6) Finally it updates the version number in the DB.

I use "Alter or Create procedure/trigger" etc.

Regards

Cornie