That really sucks, and I'll admit, I'd be pissed also. Since you lease the land, to me, that means you have SOLE hunting rights and again, JMO, I think that even means no family.
I really don't blame you for getting out of the lease. I don't mind sharing hunting property with someone, as long as we have an understanding of where each other is at all times to ensure that we both enter and leave the woods safely.

I don't believe I'd ever share a woods that I lease with that guy's family, who isn't paying a dime.

An option... Maybe you could ask the land lord if he'dallow you share the land with that fella and drop the lease payment?

Good luck,