How to create new OneNote notebook via custom content type in a doc set and open in OneNote Online?

[Eric Riehl]

I have a requirement on a current project to allow creation of a OneNote web app notebook within a document set in a SharePoint Online document library where we have custom content types. I have added "Notebook.one" as the template for a "Notebook" content type but the experience is not great. The library is set to open files in the browser.

When the user goes to add a new OneNote notebook instead of OneNote web app opening the desktop version of OneNote opens, and also presents this message: 

When they click ok the notebook is opened and ready to edit, and the document set is updated with a new notebook always titled "New Section 1.one". At this point the notebook can be opened in either client or Online by right-clicking the file.

What we want is when the user clicks the New button and selects my custom OneNote content type for a new notebook to be created and it be opened up in OneNote Online. How can we accomplish this?

[#2]

I am having a similar problem.  Got the template to work fine but it seems to just get added in the 'open sections' of the person who created the new section from the template and they can then 'move' that section to the right notebook BUT if that notebook doesn't already exist then there's a problem.  I can't seem to create a new notebook in the SharePoint Document library and since you can't easily move notebooks this is a problem.  I want them created to begin with in SharePoint.