Forum OpenACS Q&A: Adding items to existing orders in ecommerce module

I am in the midst of porting the ecommerce module of OpenACS 3.2.5 from
cybercash to either authorize.net or intellipay. Both authorize.net
and intellipay have API's that are less extensive then cybercash.

At this stage I am going through the code to see how various scenarios
are handled to map the cybercash transactions/workflow to a new one
that fits authorize.net or intellipay.

Doing this I noticed that adding items to an existing order does NOT
change the amount charged to the creditcard. Despite the note the user
will be automatically billed for this item when it ships (in
admin/ecommerce/orders/items-add-2.tcl).

Has anyone found the same and maybe even a work around for it? I would
like to move to OpenACS 4 in the future and am open to put my efforts
in adding a different creditcard gateway to the new version instead.