Hi Cetin,
There is one Listbox (Parent 'A') and one Grid (Child 'B').

The BufferOveride on both tables = 1 (Use forms setting, Form.Buffer
is set to 0 (None))

BTW, if I remove the relationship in the DE and set the B's Filter to
field = A.field, everything works a expected. When B has many records
the performance when changing 'A' record pointer is slow.

Thanks,