I'm filing Form 1040X for 2020. The original tax return showed a refund of $1,000.  The client has received the $1,000 refund from the IRS.  A mistake was made on the return and the refund should have been $1,700 instead of $1,000.  The Form 1040X properly shows that the taxpayer is due an additional refund of $700.  The problem is that the efile authorization form (Form 8879) shows the gross refund of $1,700 instead of the $700 refund listed on the Form 1040X.  Do I have to have the client sign Form 8879 to file an amended tax return?  If yes, how do I generate a Form 8879 that only shows the refund listed on the Form 1040X?