My spontaneous idea would be to do it with a unique tag, like weisser-rabe suggested.

Please note that only the first 5 tags are indexed. If you post in a community, the community counts as first tag, then only 4 tags are available.

For example, you could use bitofblue as one of the first 4 tags and link the series with bitofblue. As far as I know, you can add the tag to this post later by editing it. I'm not sure if this works with the indexing afterwards, you would have to try it out.

I hope you understand roughly what I mean.