You must have seen the response in your "Notifications" - the messages there are in the order posted, and not separated by group or topic. It actually is in the MAC group postings.
I have not posted anything stating milk thistle added to NAC is beneficial - that is a claim by one or more manufacturers, unsupported by evidence. NAC itself is a liver detoxifier as well as a mucolytic (mucus thinner), so my original remark was a question as to why the person in the original message wanted the combo.
It is likely a case where more different ingredients are not necessarily better, but that it depends on the purpose. So, if you want a mucolytic, you can take NAC as long as it is not problematic for you. If you want a liver detoxifier, research the best one out there (I have not) and use that.

Have you use NAC(ysteine) or another mucolytic, like guaifenesin (one brand is Mucinex)?

Sue