How to refresh Custom child form when called from parent form

Hi All,

Iam developing 2 custom forms one master and another detail .when clicked on the multi record  line of the custom form it opens the detail form and it is queried.

on each click on the records on master form it opens  up a new detail form , my requirement is to refresh the detail form instead of opening a new form all together.

user wants the similar  functionally  as it is happening in standard forms ( ex purchase order form , when clicked on record indicator on line it opens up the shipment form and refreshes when we click on the second line)