Tax Year Prior to 2020: Sold ESPP stock purchased before company split into 2 different companies. Form 3922 is incorrect.

I have been in my company ESPP program for many years. The company, A, split itself into 2 entities. I ended up with stock in both companies. I now work for company B.

I sold company A stock a couple years ago and claimed the discount as income.

I am now selling some of company B stock that came from this split.

All of the income from the discount was already reported.

However, company B stock did not officially exist on the purchase dates reported on the 1099-B.

How do I report this?