Customer deliveries grid : show an attribute of the linked sale order

Hi!

In the customer deliveries grid, I would like to show an attribute of the linked sale order (and be able to search by this attribute).

But the customer delivery → sale order link is special, it goes via the « originId » / « originTypeSelect » combo, and adding a field this way :
<field name="origin.externalReference" />
will not work.

How do I do to access and show an attribute of the « origin » entity?

Thanks a lot!