Can my solo 401k invest with a SDIRA?

[Olivia Dansereau]

Is it possible to my solo 401k to co-invest with my daughter's SDIRA? I wasn't sure if this was prohibited as neither of us benefit, only the retirement accounts see a return. 

I'm wanting to open an SDIRA for my child as I pay her a small wage here and there to help with admin activities  (envelope stuffing, etc) but would also like to use that SDIRA as a minority holder on investments so that I can help boost her retirement account from a young age. 

Any ways to make this happen without getting into trouble?