I think since this has gone out of the hand, it's better to suspended this season and from the next season make a strict rule that no one is allowed to send merit to any post.
I would say that the contest still has to end if nothing at least because of the sponsor. (sounds like a serious sports competition)
If anyone found to send merit to a post that contains his nomination or even do not contain his nomination they will be just disqualified. Consider this, when a name is always in front of you, you are biased to mention the name.
So, what about merited voting posts? whether they will be taken into consideration or he will be suspended like the one who sent the merit?
if it will be such a strict rule I can give merits to random posts, and influence, for example, others to be rejected.