Addition of row based on Subform View type

Hi there,

Straight to the point, if I use Subform View type List, I want the row is actually added when I click on the Done button, instead of added as soon as I click on the Add row button.

My use case, I have:

1. A subform in the List view, has a field named: Selected Participants (the value of this field will be filled by deluge by picking from multiple fields Department, Section, Title)

2. A field in the main form named: Total Participants (roll-up value from all rows in that subform, using deluge)

total_qty = 0;
for each line in c_Participants_Selection_sf
{
total_qty = total_qty + line.sf_Selected_Participants_nu;
}
input.c_Total_Participants_nu = total_qty;

The issue is, as soon as I click on the Add row button, the workflow will run, despite neither Department, Section nor Title being picked.

Or if you guys have another idea?

Much appreciated.

P/S: If I use the above code in the On User input of Selected Participants - because this field is filled by Deluge, somehow it does not work as usual.