A couple of things.
I assume when you say that the front end is still in Access that you mean that the back end is no longer in Access. Of course, if that is the case, you won't be able to affect any change by modifying the relationships in Access, as suggested earlier.
I'm always awed when someone believes that they need to delete records (especially records from a major table) unless there is an error that occurred or unless the database is being retrofitted. I usually keep data forever in an OLTP system and just mark out of date data with some kind of valid flag. I don't normally display data that is marked invalid and I don't delete data except as a part of a major system maintenance, just mark it as invalid.
As far as cascading deletes go: your DBAs did not set up cascading deletes (like you said you asked them to do) if you are exhibiting this problem and describing it accurately to us. I personally believe that cascading deletes in an OLTP system is generally a very bad idea.