Legal Question in Wills and Trusts in California

Depends on what happens to him. You should contact someone like myself for a full consultation. This is more complicated than an online forum can answer.

A power of attorney is almost certainly insufficient as an estate planning tool. Among other things, the power expires at the time of your father's death. Your current mother-in-law may have a community property interest in the business as well.

Your father needs to meet with an estate planning attorney to review his options, and make sure his estate is handled the way he wants.

Unless there's a prenuptial agreement, then everything your father earns during his marriage is community property. When there's a family owned business, this means that if he's actively involved in the company, then a portion of the increase in value of the company during the marriage becomes community property, half owned by the spouse. There are a couple of different ways of calculating this community property interest - it can turn into battling accountants in the event of a divorce. The best thing for your father to do is to create an estate plan with a forced election so that upon his death his wife has to choose between inheriting what he leaves her intentionally, or asserting a community property interest in the business (and perhaps other assets).