We at Casetext are interested in this space as well. Our annotations technology will undergo some major improvements in the near future, but even the way they are today may be sufficient to meet your needs. Hit me up (jake at casetext.com) if you want to work together to make this a reality. Here's an example of what docs look like on Casetext now: https://casetext.com/contract/simple-agreement-for-future-eq...