OData: Create operation on entity with associated entity?

Given the following:

I am modeling a document that has both header and items.

This results in two entities with an association. So far so good.

When I try and create the document, I will ideally want to pass the header and items (i.e. the complete document) in one go (assumedly via an HTTP PUT).

Is this possible? In practice, how will my HTTP request look that creates the entity in its entirety?

Furthermore, (and this is my great concern): Will SAPUI5 support binding to an OData model in this way as to support this?

Let's assume the following simplistic model:

Header:

DocumentNumber

Items:

DocumentNumber

ItemNumber

Material

Quantity