This is correct: "but once the form is created it seems to exist in its own silo, independent of the customer information."

The QB data is a Relational Database; once the Customer info is brought into the form, you also can update it right there, and Not feed that into the Customer Center, because now the Transaction Exists and this is its own Database Table of info. The only option would be to Select a different customer, then reselect the original customer, to get the Transaction to pull from Customer Info, fresh.