Katherine Jackson has hired an attorney

Jackson family sources tell us there's a bitter dispute over who will call the shots in probating Michael Jackson's will.

Katherine Jackson has hired an attorney -- Londell McMillan -- and we're told it's a done deal that McMillan will challenge the co-executors Michael selected. We're told most of the brothers -- Randy the notable exception -- are angry that McMillan has asserted himself by challenging co-executors John Branca and John McClain, both long time advisors and friends of M.J.

Ultimately, Joe Jackson has asserted his influence over Katherine to hire McMillan for the dirty work. We're told Katherine is really being manipulated and doesn't even have real objections to Branca and McMillan.

Randy is coy on who Joe and McMillan wants as executor instead, but the family is worried Joe and McMillan wants someone who will do anything but look out for the best interests of the estate -- especially since Joe is cut out of the will like a bad cancer.