problem loading data form via controller

The form A contains the form B.
The Form A is updated with each onRecordSelection of form C.
I must load the controller of form B and can’t load through foundset because there are also the forms D and E have the same foundset of form B and the data should be handled.
If you pass in onShow () of the form B the displayed data is correct.
But not always go in onShow.
Where and how I can update the controller of the form B ?
txs

Who’s on first?

david:
Who’s on first?

It must be the short-stopper…