Legal Question in Wills and Trusts in California

They have the right to contest the Will if your mother had adopted them, but otherwise they would not be beneficiaries unless directly named in the Will. You probably need to give all the details to an estate attorney and have him/her contact the two stepdaughters informing them of what rights they have and do not have. That would be cheaper than letting them first get an attorney and sue and then successfully contest their claim [if they end up dropping it]. At least you would know where you stand legally sand whether you need probate your mother's Will and how to do it in the least expensive manner.

If you want, you can contact me for further information.

It doesn't sound like they have standing, since the will that disinherited them was the one that gave everything to your mother, and is not the one they are challenging. If they set aside your mother's will, they would not receive anything as pointed out by Mr. Shers.

I do recommend that you talk to an attorney familiar with probate litigation. Their may be other problems with their will contest as well.