This article will explain how to program your Yahoo Store so a shopper can click on multiple items and add them all to the shopping cart with one simple "add-all-checked-to-cart" button click.
This article is intended for someone who already has experience progamming Yahoo Store and is familiar with Yahoo's documentation and basic store tags and understands HTML fields.
An example of a basic Yahoo store-tag is simply to view the shopping cart within an link.
The view cart code is: View Cart
More information about store tags can be found here
If you call Yahoo support, that might be a problem...
The front line support staff is very good at what they do but they may not be able to help you with this issue. I already talked to Yahoo tech support but this is a very advanced undocumented feature of Yahoo store that required a lot of research and digging to figure out and a lot of web designers/programmers do things differently.