Student or Learner
As ABC company is only business agent of both QQQ product and GGG central control program. Therefore, the additional control work should be carried out by the ABC company.
A person told me a word “ portfolio” is suitable to use in the about sentence. Grateful if anyone could help to modify the above sentence with the word "portfolio”.
I do not see how "portfolio" can be used in these sentences as they stand. It is generally used to refer to a range of investments or a person's collection of work used to sell their abilities.
Quite apart from that, there is a problem with the sentences. The first one starts with "as", but has no logical alternative within it.
I would suggest the sentences will be better as ABC company is the only business agent for both QQQQ and the GGGG central control program and therefore any additional [control work] should be carried out by ABC.
It is not clear what "control work" means.
One possible way to use "portfolio":
In its portfolio of clients, ABC company has QQQQ and CCCC central control program...