:: We sell systems powered by Firebird SQL,customers ask
:: something new every month that means to add a new field or a
:: new table, we make SQL scripts to path the database but the
:: hard part is to tell our customers have to apply the
:: patches, normally we do it our selves connecting to the
:: customer server remotly.

You can use IBAdmin, or IBExpert to generate a diff script and then execute
that.