Will and IRA's

[ncombs]

Simple question. My mother in law has a will that says to split all assests equally among her children. She also has IRA accounts. We don't know who is listed as a beneficiary on the IRA's. The will is silent in regards to the IRA's. Upon her death, does the IRA's go to the beneficaries, THEN what left gets split up? Or does the IRA's get lumped into all the assets that get divided up?