hey David,As a broker, I have several options if you're looking to only touch the equity in a second position lien on investment property. 

You could then choose a broad based index fund if you wanted to invest in the market.  

I own 12-doors there and help others invest there for a living.Of my 12-doors, 4 of them are comprised of two duplexes.

I started investing in RE when I was 26.

Additionally, if he’s legally and financially tied to the property, it might limit his flexibility if he wants to make major life changes, like moving or starting his own investment ventures.Ultimately, the decision depends on how involved you want him to be in the financial side of the property and how much risk he’s willing to take. 

Investment Info:Single-family residence fix & flip investment.

Could you send me your email (feel free to format it like “name [at] domain [dot] com” to avoid filters), and I’ll send you the link directly.Also, I’d love to hear more about your background:How long you’ve been in property managementIf you’re currently involved in multifamily investments or looking to expand into that spaceWhether you’re exploring tools for your own portfolio or considering something broaderLooking forward to hearing more and seeing if there’s a fit!

. :) It sounds like you are looking for a specific investment opportunity? 

I love hearing the investing enthusiasm of our youth!

Welcome to BiggerPockets Jason and good luck investing!