Regardless of their team/friends/relatives or Alt account, if you have any doubts about them or cheated in the campaign, you can report it to the Bounty/campaign manager, and valid evidence.
But from the data I see 9 accounts above that you suspect, I can prove by the address they use and their Alt account is connected.
You can see below.
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OP, if you have time, try checking the Alt linked above, whether they cheated in the campaign / Bounty or not, if you find it, you can report it to the manager.