Can't be done. The problem is there is not way to detect what a series is.
If it was a common starting name and then a number it could be done but look at the series below I copies from the challenge. There is not way to detect that those cacher are in a series. You have to read and understand the cache description to do that and that is out of the scope of a challenge checker
VILLAGE SIGNS
1 GC5JH0Q Team Hippo 203 Nettlebed 01/06/2015
2 GC46VJ4 Smokeypugs 1 Dagnall 08/03/2015
3 GC5Q6RT ryo62 258 Meldreth 30/07/2015
4 GC5E839 ryo62 196 Shepreth 30/07/2015
5 GC5E84X ryo62 197 Foxton 30/07/2015
6 GC5QH35 ryo62 259 Barrington 30/07/2015
