Microsoft OneNote might be of interest. It's meant to be a " digital three ring binder" and is VERY flexible, just like a paper notebook would be. It's not very well known, but it's an outstanding program.
You can save all or part of a notebook as a PDF at any time, so sharing is easy.
I use OneNote for many,many projects, including genealogy.
If you have Office 2010 or 2013, you probably already have it on your 'puter. If not, you can try it free to see what you think.
Many helpful videos, etc. are on the office-dot-com site to get you started.
Good luck, whichever program you choose!