Form 7203 Impossible to Fill Out

My father and I started our little S Corp 20 years ago. We didn't "purchase" stock. We are just 50/50 owners with no initial cash input. We never kept a stock basis worksheet (shame on us, I guess). I have no idea how I'm supposed to fill out the new Form 7203. I don't even have K1s from that long ago. Any suggestions? Can I still submit my taxes without filling it out completely? I no longer get an error, as long as I put a Stock Block of 1. But that's all I entered. Ugh!!! By the way, my father uses HR Block and the form doesn't even exist in the desktop version so he was able to e-file with no issues.