Should I change the acquire date to reflect the correct stock i sold?

[tpe]

Assumption: I will import 1099-B from two brokers.

Here is my example, I sold 100 shares of  stock ABC.  I think It will be reported by Broker A in 1099-B for the stock I purchased using the broker A in June 2019. However I had purchased the same stock of 100 shares using  Broker B in April 2019. With FIFO (first in first out) rule, I think I will modify the cost base for the sale record reported by the Broker A in the form of 8494 to use the purchase amount from the same stock i purchased in April with the Broker B. The question i have "Should I also change the acquire date to reflect the purchase date of the stocks I bought in April with the broker B? Can I just delete this existing record and put in a new record with the acquire date and acquire amount of the stock I purchased using the Broker B in April rather than doing cost base adjustment with the existing record? Which way you think IRS thinks is right to do?

[Critter]

You should not need to edit anything ... you told broker A to sell the shares you had in that account.  If you had wanted to sell the older stock you should have sold it in the broker A account.  FIFO only works if all the stock was in the same account ... and broker's usually follow this rule unless you instruct  them otherwise.  And in your case you did ... you instructed broker A to sell what was in that account.   Changing things now to reflect a better position for your bottom line is begging for an audit.  This is why brokers have to keep track of basis and report it on the Sch A ... so there is very little reason to make any corrections except for uncovered sales.