I'll start by saying "here be dragons"
If the customer wants to continue to do data entry in
just the embedded version, then you could use
DataFlex DataPump to update the data in the SQL database on a regular schedule (that's exactly what it was designed to do).
But, if they will be doing active data entry in
both systems, that would likely lead to a
very complicated situation! You'd essentially have to write a data "merge" process to sync the data in both systems with each other.
So, without knowing more about the whys of needing both systems to be live, it's very difficult to try to advise you.