The Kiwi currently holds the WBO heavyweight belt and called out WBA 'super' and IBF holder Joshua last week following talk of a potential unification bout.
A 40-60 share in favour of Joshua has been proposed when it comes to sorting out the money but David Higgins, who is a director of Parker's promoters Duco Events, has now cast doubt on the fights.
Higgins says he reviewed a "ridiculous" offer from Hearn, adding that the Englishman is not taking the size and stature of the proposed unification bout seriously with his current stance.
"I got this weird email from Eddie's email address, but he must have been hacked," Higgins exclusively told Sky Sports. "He made the most ridiculously low offer. It could have been the most insulting offer in boxing history.
"To expect 40 per cent is actually quite reasonable, because you have earned it, and it's a unification.
"Of course I have mentioned it [to Joseph Parker] and he just laughed like I did."