Hi CertifiedJewelsdotcom,
When you are creating a given listing, whether through Auctiva's lister page or eBay's "Sell your Item" form, you can only specify two eBay store categories for the item to appear in. I don't believe it is possible to place an item in more then two eBay store categories, but you may want to contact eBay's customer support department for further clarification in that regard.
Any additional questions or concerns? Please feel free to contact our customer support department using the appropriate link on our help page:
http://www.auctiva.com/free-auction-software-help/help.aspx-Mike