Hi there.
I'm new to this to, and am still acclimating myself with everything. So far I've only posted some listings: I haven't even begun to organize my 'store' and storefront, nor work with all the other fantastic tools/personalization options on the basic FREE model that's offered here. (Still can't go over that they're giving this much for FREE: no charged fees).
Anyway, that said, as I've been sifting through some pages and getting familiar with how to set up and personalize a 'store' I just happened to notice something that I think pertains to what you're asking about here, (RE: how to edit a listing on the auctiva host site AFTER you've already posted it to ebay.
Not sure if this is what you're looking for or not, but I thought if it just happens to be I might pass along ....
On the Auctiva home screen hit the 'store' tab up near the upper right hand side of screen. From there hit tab for 'edit store items'. Your screen then should populate with a listing of all your currently running listings that you've posted through auctiva. BUT ...
From there I'm not clear if you can edit (edit the photos on your listing) directly through auctiva -- or -- if you have to link to revise via ebay. And the latter is the case, then ebay will probably assert FEES of some kind.
Anyway there you for whatever it's worth. -- Best, Deana
PS: If this isn't what you were looking for and you were able to find the info. then please let me, as I'm quite sure it will be useful for me to know this information for future use.