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Google only approve one company apply one account if sell the same products.
and if the the account has diversificed keywords, but only the "more exact match" would showed.
I don't know how does the google system working.
Google will accept affiliates, but they have to let everyone know that they're affiliates in the ads they create.
The main company and the affiliate are using separate Adwords accounts. As far as I know, Google doesn't allow multiple accounts.