Repairing buggy query server-side – without changes in the app

More external apps are accessing our ERP SW database. As we were adding some columns into our structure, some queries from the external app become buggy because they are not specifying the targeted table in the query and errors out with Ambiguous column name… message.

The app vendor is inaccesible. We cannot repair the query from the app point nor change our structure (it’s for more customers).

Can we do something at the database server level?