Hi Sheila,
Sorry for taking so long to respond. Great question.
If another publisher accepts your submission, come to the site and find your submission (you can use the search box or visit your profile or whatever). At the bottom, you’ll see a link you can use to “Edit your piece”. If it’s not there, click “permalink” to get it. You can change the contents of your submission to indicate that the story has been accepted somewhere else and provide a link to the other site (if they have one). I think it’s also possible for you to delete your own submission if you’d rather do that, but I think everyone wins more if you just edit it.
Dave.