When filing life insurance claim, fill W-9 or W-8BEN

So my dad passed away a litle over a month ago out of country, and we're currently trying to file his life insurance policy claim. We're required to fill out a W-9 as well, but since my mom, the beneficiary, is undocumented, we didn't want to claim her as a U.S Person on the form. The insurance company reps said to fill out a W-8BEN instead.

After some research, apparently tax laws and different from immigration laws, and depending on either the green card test or the substantial presence test, even illegal immigrants would be classified as a resident alien. Tax law only have 2 categories for tax payers, resident or nonresident alien, so I'm not sure if resident alien would count as a U.S Person in terms of tax law. Anyone have any ideas on this?

The tax forms are probably going to be used on taxes on the interest accrued from the proceeds, so not sure which one to fill out.

Undocumented immigrants can and are classified as resident aliens for tax purposes. Yes, tax law refers to resident aliens as continually residing in the United States for more than 1 year. Nonresident aliens are those that have a foreign address and only live in the U.S for months at a time.

Your mom will put in her ITIN number on the W-9 where it asks for her social security number. She doesn’t need a social to file W-9. If she doesn’t have an ITIN, she’ll need to apply for one

Thanks! She does have a social. So claiming to be a "other U.S. Persons" won't be used against her as falsely claiming USC if she adjusts in the future right?

No. She’s not claiming to be a USC on the W-9. The W-9 only asks for a social security number or an ITIN that you use at tax time for the purpose of reporting income

page 2 of W-9

IRS Resident Alien definition

IRS Substantial Present Test

I'm talking about the signature part, where it says:

I guess the "or" kinda makes it that you're not claiming to be a USC, but other U.S. person.