dynamically add fields to a From Grid Control

a customer wants to a customized "LedgerTransAccount" Form

They want to have a checkbox to activate the "Transaction Origin". If the checkbox is marked true the grind on the form should show fields for "Module" and LedgerAccount of the Transaction Origin.

So it must be something dynamic because you do not know how many fields you have to add

How can I realize s.th. like this?