As mentioned in !37 (merged) , it would be better to only flag the ttB sub-process as signal, to avoid producing (in principle empty) migration matrices for ttcc and ttjj.
I've added in the sample configs a list of subprocesses to be flagged as signal. The is_signal flag is then inserted when filling in the sample template.
If you work with the insertSamples.py script instead of the --samples argument of the plotter, don't forget to regenerate the sample list.