Based on your previous posts (like from July) we are not sure what you have done or filed. Like if you each filed as MFS separately then wait until each return has been fully processed and you got the refunds or paid the tax due on each one. Then you can Amend one of the MFS returns to be a Single Joint return.
How to amend separate returns to Joint
https://ttlc.intuit.com/questions/1899507-how-do-i-amend-a-separate-return-to-married-filing-jointly
