Wow... I had a doubt and you had an entire book about that topic.
Your info will be very useful.
Unfortunately we have the same problem than before: HKMDb does not allow alias in the prod. companies' names. (If "International Films" changed its name to "Motion Picture and General Investment" in 1957, HKMDb splits that company). I think the only possible solution is using Mr. Dleedlee system: link them.
About your suggestion, I checked your info and I think our symbols of Cathay (MP & GI) 電懋 are not correct, WebPAC says (for example, in the film "Mambo Girl") that they are only an abbreviation of my symbols... I did not see them in your logos neither...
So, if nobody stops me in
7 days, I will merge MP & GI with Motion Picture and General Investment (as you wanted).