I meant SPLIT when I wrote that.
But your point about mySiStripRecHits is correct, it's also bad to use it here: this module is defined in the test area while the modification function is in general area.

I can see that splitter_tracking_RunI_setup_cff.py is useful to be in general place.
I suggest that instead of using actual names, you define a function here that would take "mySiStripRecHits" as an argument. You can then call it from the test cfg.