Question:

Can a veteran with employable benefits sit in or help out at a family business. It's all volunteer, they aren't getting paid at all.  

Jim's Reply:

The veteran who is rated as TDIU isn't allowed gainful employment. Gainful employment is pretty much anything that earns you more than the federal poverty wage.
 

You can volunteer for anything and any amount of time you care to give. If you aren't earning a paycheck, no worries. Good luck!