Will Call Flag on specific items

I am adding shipping based on a column value. That is working fine. I do, however, have a column with with a check box value (a JPG of the item screen with "Add to Cart" button is attached) that allows the buyer to opt out of the shipping fees and make specific arrangements for pick up or delivery. This also works as expected unless the buyer goes back to the item screen and changes the option. It seems that only the quantity is updated when the "Add to Cart" button is used for an item that is already in the cart. How do update the "DO NOT SHIP" column and, accordingly, "shipping amount" column for this item when the visitor/buyer edits the quantity or shipping option?

Whoops! I think I asked to soon. I changed to $ATC_AddIfIn = 4 (replace qty) and that seems to update the other columns as well. I'll do some more testing, but I think that will take care of my issue.

Thanks...

in the eCart object, you can set the do not ship column to be unique.

This method would allow for the shopper to purchase the item twice, once with the shipping and once without. the shipping option would trigger a unique line item,

of course, if you don't want the shopper to be able to purchase with and without shipping on the item at the same time, using the the replace Quantity option in the add to cart button, as you have done, is the way to go.