Starting to look like a shell game.  What other assets were in the estate that generated income?  You can't just say that the money the beneficiaries got was just the proceeds from the land sale.  The money came from the income first, then the principal.  There must have been income from other sources because otherwise you wouldn't have anything to pay tax on.  

If there was net income, it's considered to have been distributed.  You don't have a choice.  But it probably results in less tax to the beneficiaries.  They may have already filed their returns, though, and won't appreciate not being told to wait for K-1s.

The one who got land is probably also included in the group of those who are considered to have received income.  But I always have to look that one up.