Grid with Field link to form parameter in 2 directions not possible?

Hi,
This is probably a newbee question,
I have a grid with a lookup field, the Field has a link to a form application. The parameter is the target table primkey.
I can select add and delete records within the target Form, perfect.
However on exit of the target form the Field in the grid is not updated with the new ID.
I guess this is not possible, ore I am missing something, any workaround?