You are responsible for your business, and making sure everyone is trained. Relatives are notorious screw ups, otherwise they wouldn’t be hitting up the Aunties for jobs.

You didn’t make sure he knew how to do it? Trust, but verify.

Even with experience, every job is different and requires a different level of attention. YDI for not managing your business properly and ensuring he had all the knowledge prior, as well as following up to ensure he understood his duties.

TRAINING... which means you watch what he does to make sure he does it right. That's a harsh lesson to learn.

Don’t you train your employees?

All jobs I've worked at had training for new hires. Yeah, you could trust your family, but you should also not leave anyone alone to do the job until you at least witness them doing the job properly at least once without guidance from you. Before you even let him go about doing it, you should have verified he could do it. An hour watching him do the job the first few times could have saved you a ton of money.

sounds like he was pocketing it.

YDI for nepotism.