Report Wash Sale/Incorrect Basis Across Brokerages

Hello!

I had a question on how to enter this:

I had a wash sale a few years ago from a stock sale from brokerage A at a loss and purchased the shares at brokerage B within 30 days. I noted the wash sale on my taxes that year and disallowed the entire loss from Brokerage A’s 1099-B.

Of course, the 1099-B from brokerage B would not report the correct basis including the wash from the loss when I sold the stock in 2024.

Am I free to edit the basis from the imported 1099-B or would that flag me for audit? How could I report it if not?

Also an adjacent question:

I had a stock purchased directly from a company in 2020. A few years later they went public. I had to transfer the shares to my own Brokerage to sell, but their cost basis does not reflect my acutal basis at the time of purchase. Am I free to adjust the basis on the Brokerage’s 1099-B to the correct original investment amount, or would this flag? If not, how else can I report it?

Thank you in advance for any advice!