What sort of vehicle Sheri? Heavy, or Ute/Car Trailer loads, are you looking for attendees to achieve Unit Standard 1753 (Load and unload a general freight vehicle).

When looking at the chain of responsibility, yes it is the drivers but there is also shared responsibility for load restraint, some years ago I would not allow a vehicle to leave our premises until he restrained the load correctly. I am unaware of any formal courses but maybe contact the road transport association.

https://www.trdrivertraining.co.nz/courses/load-restraint-load-unload-a-goods-service-vehicle/

https://avtnz.co.nz/services/load-restraint/

https://www.drivingtests.co.nz/course/truck-load-security/

The official New Zealand truck loading code

Light vehicle load security: https://www.drivingtests.co.nz/course/load-restraint/
Heavy vehicle load security: https://www.drivingtests.co.nz/course/truck-load-security/
If you need a trainer, TR Group can run courses with or without the unit standard: https://www.trdrivertraining.co.nz/courses/load-restraint-load-unload-a-goods-service-vehicle/
You might also want to look at trailer coupling training if you're also doing trailer swaps

Hi Sheri HSE global have an entire division designated to provide this. HSEglobal.com

thank you