You can always file an "amended" return but I am not sure the effort would be worth it IMO. I suggest you just send the 8453 with whatever 8949s TT created. If your transactions were reported on a 1099-B you do not have to send those with your Forms to the IRS Austin TX address. You are correct the 8453 says to send the 8949s (not 1099-Bs)
This is IMO the simplest way out of the problem. Unless you have pages and pages of 8949s (mine where just 2 so three pages which is just an ordinary 1st class stamp and dropped in a mailbox).
