I'm building an image on the dunfell branch.

I would like to add dataclasses module in python3. For that I know that I should add it to the python3-manifest.json.

I tried to add my new manifest file in SRC_URI using a bbappend. It didn't work as the manifest file is red by a anonymous python function on parsing:

filename = os.path.join(d.getVar('THISDIR'), 'python3', 'python3-manifest.json') 

What should I do to add dataclasses to my python3 installation? What is the suggested method or best practice for that operation? 

I would like to avoid forking openembedded-core just for that.

Thank you

Perceval