To allow a change in shipping after a bid would enable the seller to boost the fee when someone already committed an amount based on the original amount. While allowing only the addition of another option wouldn't have that particular problem, the question for eBay is whether the demand for such would be enough to outweigh the efforts and potential other problems that might come up.
You can issue an invoice with amended shipping to the bidder if s/he wins.* If s/he cannot bid because you have your Buyer Requirements set to block those whose Primary Shipping Address is in a location you don't ship to, add him/her to your exemption list. Go to the Site Map (link at the bottom of this and most ebay.com pages) Sell Section (use the shortcut at the top--it's a long scroll down) and you'll find the link to that (actually the link that leads to them is for your Blocked Bidders/Buyers List which takes you to a "Bidder Management" page with several options) and several other useful seller tools.
*Which should also, in my opinion, be limited to adding an option without changing the existing options; but they don't listen to me and doing so overrides the terms of the listing which is often abused by the seller which creates problems for the buyer.
wooden_flower Volunteer Community Mentor.
