WA probate, if children are listed beneficiaries to 401K and life insurance benefits, can wife try to get the money

I see at least four issues here:

1. Does the surviving wife have any ability to upset the Decedent's havng designated his sons as Beneficiaries? In my experience: No. Although if any of the sons is a minor, his share will likely be paid to a custodian or guardian for his benefit.

2. Were either the 401(k) plan benefits or the insurance policies community property? If so, then the surviving wife may have a claim for half of whatever benefit was community property. The usual way these benefits become community is their having been acquired as a result of the Decedent's employment or otherwise acquired with community funds.

3. If any was community property, did the surviving wife consent to the sons' having been named as designated Beneficiaries? If so, then she has likely lost her right to complain.

4. Were either the plan benefits or the policies subject to ERISA (the federal Employee Retirement Income Security Act)? If so, then federal ERISA law may override Washington community property law regarding the disposition of the proceeds.

I've handled numbers of these cases, and they resolve on the basis of their facts. Read the contracts & see what they say. Determine how they were acquired.

Specifically on the 401(k) plan, if it is subject to ERISA then the spouse is the beneficiary unless the spouse signs a waiver. Ask the plan administrator to send a copy of the spousal consent or waiver.

Instructions for such plans typically read
"If you are married and designate someone other than your spouse as the primary beneficiary, your spouse’s consent is required and the signature must be notarized or witnessed by the plan administrator.
If you are not married when you complete the beneficiary designation form and you later become married,
or if you later become married to a different person, the designations previously made will automatically be
revoked; any death benefits will be paid to your then spouse unless a new beneficiary designation form is
completed and the Consent of Spouse is signed and witnessed."