Could anyone point me in the right direction regarding researching the following?

Is there anything in ERISA which precludes a son (not actively employed by father's company) to perform the investment advisory duties of father's company 401(k) plan?

Section 406(b)(1) of ERISA and Section 4975©(1)(E) of the Internal Revenue Code fo 1986.

Laymans terms - Not if the father/company, using proper due diligence as a fiducairy, show the son is the right one for the job, based on all the important stuff like cost, experience, objectiveness, etc.

Is the son compensated?

JanetM: You may want to take a look at 29 CFR Section 2550.408b-2(e)(2) and Example (6) of -2(f) and see if that changes your mind. (Identical provisions are in the Treasury Regulations interpreting Section 4975©).

QDRO: If there is no compensation, direct or indirect (as unlikely a scenario as that may seem), it could nonetheless be a PT (e.g., if the son can then "tout" his experience as an investment advisor to the XYZ Company Retirement Plan); or, perhaps not.

Isn't there a NASD or RIA rule that prohibits this ?

Yes the son would be compensated.

Thanks for all the comments! You have given me a great starting point for researching.