Create link between Handling Unit and Inbound Delivery through API part2

Hi however to nexus done api inbound Delivery fig with Handling Unit?
Handling Unit was created done API with customized numbering. Wanted to adhd refrenceDocumentNumber (Inbound Delivery) The HU was created but the added Inbound Delivery fig not.

Tried to make an Handling Unit point with the aforesaid refrenceDocumentNumber and refrenceDocumentNumberItem but API mistake says the genitor Handling Unit has nary refrenceDocumentNumber.

What is the process nexus Inbound Delivery and Handling Unit done API?