Pass Field Value from Linked Form(From Select Field) To Main Form

Good Afternoon All,
Please I need your help to solve what I believe should be simple but I have not been able to achieve it.
I created linked form to edit a select field (See the attached diagram) when adding a new value to the combo box, I want the value passed to the main form using onafterinsert event of the linked form. I tried sc_redir() but it didn’t work.

After submitting, I want the vessel_name passed to the main form dynamically.