I have a relative who has both traditional and Roth 401(k) accounts under an old employer plan at Vanguard. I know these must be separate accounts, because that's required and I've found multiple IRS pages confirming that, but Vanguard is apparently not showing the accounts. It will for any given year show how much of the contribution was Roth vs. pre-tax, but my relative still doesn't quite believe me about the accounts being separate because Vanguard isn't showing it.
I haven't used the retirement plan participant login at Vanguard for many years, so I don't know how to help him find the right info (which would be so easy to find in an individual login). Any tips?