Add more OTC instruments

I am invested in a few companies that are traded OTC. Some of them I am able to add to my portfolio (SpaceX, Impossible Foods), but others I am not (Flexport, H2O.ai, Cohesity, etc.)

What is the logic by which you make only some OTC instruments available in the Search? How can I add all other OTC instruments to track everything in one place. 

I decided to migrate to Seeking Alpha only because I hoped to have all of my investments trackable in one place. If it's not happening, then it might be not the right place for people like me