Add and delete rows in the imported Bank Statement

Is it possible to add and delete rows in the imported Bank Statement? If I create the Bank Statement manually, I can add and delete rows, but if I have imported it, I can only match rows and add Payments to the existing row.
The first problem is that Bank transaction and Bank fee are summed up on the same line in the file, but we need to handle them separately.
Second problem is currency rate. If the payment is created with currency rate A, but bank transaction done with rate B, then there will be a variance on the transaction.
Then we want to create a new line with Type = Bank Adjustment.
Any idea how to do this?