Write out story A’s backstory in a ‘New story,’ and when story A is published, copy the link under the backstory. Keep it as a draft, and do the same for the next several stories. At that point, you can self publish them as an anthology, linking back to the originals. You might gain further readership that way.
Many of the backstories I’ve read are about where the writer got their inspiration, so it could also be educational.