Version 11.5.10.2 - OEXOEORD - usage of descriptive flexfield

I initially asked this question in the Forms group - but perhaps Order Management group could also address the issue.

I am using the descriptive flexfield on OEXOEORD form, for Additional Header Information - and I default the values in the context segments from SQL queries against the matching customer address table - that corresponds to the ship_to_location on the order. On initial entry, the flow from customer to Order works as expected.  However, if the order is changed so that a different shipto is chosen, the flexfield data does not refresh with the new cusomer information.

I would expect the flexfield query mechanism to refire after a change is made to a referenced field.  How can I make this work without adding code to CUSTOM.pll?