disown, disinherit

Disown or disown means to deny relationship to or responsibility for--
He attempted to disown the child; and asked for a paternity test.
They asked the judge if they could disown their son, and have him declared a ward of the state.

Disinherit ot disinherit means to exclude from an inheritance, as by altering a will--
He plans to disinherit his children, and give the money to charity.
His father threatened to disinherit him if he didn't straighten up and get a job.

Now that you know that, you can say--
"It may not be possible to disinherit the children, unless you can legally disown them first."