Katie Joy from the Moon Zoo Science Team sent me some very useful links to crater chain examples. Some of the pictures are in the table below but please click on the links for lots more examples and information. She also said:"Beautiful herringbone ejecta pattern arising from many of these craters (note that there is a nice detailed research paper at http://adsabs.harvard.edu/full/1974Moon....9..415O demonstrating lab experiments of this process if people would like to know more.) "
Looking at these examples I think many of the crater chains we have found are not
in fact crater chains. We need to think bigger and look for much longer chains of secondary craters.