IANAL, and this depends on many many factors, and probably many more than you currently have on your radar given the way you've phrased your question.

Best way forward here is likely to sit down with a great lawyer and talk through the technical options you have, which will vary based on jurisdiction and setup.

If you have a good relationship with the 16%, there is probably a way to readjust the ownership levels in good faith - they will want you to be properly incentivized. You will have to make a good case for this and explain how the readjustment will work best on a technical level, and why this is going to be win-win.