Unless you have word from somebody at IOI that these bricks are officially supported, I would prefer if you just add these entries in your content pack. I don't want the responsibility of keeping specific bricks alive in the framework!
You can look at the offline elusives pack on how to add packagedefinition entries from a content pack, it is at the end of __init__.py. If you think the resources could ever be used by other content packs, maybe also add a check if they are already registered to prevent double-registration.