It is likely that many of your stored procs or SQl queries fromthe interface won't work correctly either even if you create the tables in Pervasive as every SQL database has a different flavor of SQL. What you need to do here is based on what your contract says. If it specifies which daa be will used, you need to charge the customer for any work based on their mistake of buying the wrng database. If it doesn't say, then you may be stuck fixing their error, I would ask a lawyer before I considered doing anything for free on this job. Changing databases is not generally an easy or quick task and it will cost you a lot of money if you do not charge for the work. Once they know how much you will charge to fix their error, they will be more likely to invest in the correct db.
"NOTHING is more important in a database than integrity." ESquared