Looks a messy situation, though I recall in the summer Witsel had several representatives all saying contradictory things and looking for a slice of the pie. All very unsavoury.
It seems prudent to cultivate good relations with agents who can be helpful to us down the line but we either want to sign this guy or not - I don't see how Henrotay can add anything to this for our benefit, as his "fee" would have to come out of someone elses pocket, not Everton's as we are hardly haggling to increase agent fees for this transfer.
It's a murky world.
I'm not suggesting this is the case, but this is essentially how it would work:
Everton inform the player they're willing to sign him as long as he fires his agent and signs with Henrotay. So the agent fee that would go to the player's current representative instead goes Henrotay.
Again, I'm not saying that's what's happening here, but smaller agents get pushed out of the way in similar situations all the time. It also works in reverse, where a player gets shafted because his agent has no leverage. Rough business.