Our own link to the Supplier Invoice?

We want to be able to have the link to the supplier invoice to point to our partner instead of pointing to Next. This worked in the previous API.

We don't want our users to be able to see every invoice and our partner has an authorization model which is more fine grained.

In the current API we have to send the document to Next to get a working link, and therefore everyone can see every invoice! This is not acceptable for us.

What can be done?