...
This can be accomplished by including an HTML checkbox input with the attributes class="kformCheckoutUpsell" and value="[productId]", where [productId] is the campaign product ID of the campaign product you are offering.. You can also set the quantity on these inputs using the attribute quantity. If the quantity attribute is not present, the quantity will default to 1.
Notice: kformCheckoutUpsell
kformCheckoutUpsell offers process at the same time as the main offer and will bill on the same transaction if assigned to the same
...
gateway as the main offer and Stand Alone Transaction is not checked on campaign product configuration.
If separate transactions, kformCheckoutUpsell offers might successfully bill despite a decline on the main offer.
If you want to bill the hidden charge as a separate transaction and make sure it does not bill if the main offer declines, you might want to add it as an automatically submitted upsell page.
The javascript to submit kform is:
Code Block kform.validator.formSubmit();
There are a number of scenarios in which you may wish to add additional products to the checkout page:
...