Hi Hatterswidow Do'nt worry I have changed listings and relisted via ebay as long as you do not delete the foto's on auctiva.It also takes time for auctiva to SEE the alteration.I have never had a problem with this in the past so you should be ok.
http://stores.ebay.co.uk/Simpsons-The-Online-Store
http://simpsons.ecrater.com/