The ahelp clearly says that "small" regions (too small area or too few counts) would be assigned to the largest neighbor (with the most area or the most counts). But:
It may make sense to make this parameter option and let the user decide which is appropriate for their use case ... the change is fairly trivial but need to review ahelp to make sure everything is consistent.
A what was I thinking moment.
The ahelp clearly says that "small" regions (too small area or too few counts) would be assigned to the largest neighbor (with the most area or the most counts). But:
https://github.com/cxcsds/ciao-contrib/blob/bd7b0ea7b1423e1c8268d5e19b59927a6cb5359b/bin/merge_too_small#L111
is assigning it to the smallest neighbor.
It may make sense to make this parameter option and let the user decide which is appropriate for their use case ... the change is fairly trivial but need to review ahelp to make sure everything is consistent.