Project Proposal selection when creating quotes by internal resources

We use Project Proposals when we create Quotes in Autotask. If a Project proposal is created, then presales can also log their time and we'll have a better view on the actual cost of a particular project.
At the moment it isn't possible to select the Project Proposal when creating quotes via Salesbuildr.
It should also only be possible with the internal resources to do this, not customers.
If the Project Proposal can't be created via Salesbuildr, that's no issue, think that's a bit more work then just add a dropdown with the possible existing proposals based on the selected company as this is available in the Autotask Quote wizard already.