Yes, you will need to add her financial information on the 1040X since you are both considered one taxpayer when filing Married Filing Jointly (MFJ).
According to the IRS:
"You are changing from separate to a joint return.
If
you and your spouse are changing from separate returns to a joint return,
follow these steps.
Enter in column A the amounts from your return as originally
filed or as previously adjusted (either by you or the IRS).
To determine the amounts to enter in column B
, combine the amounts from your spouse’s
return as originally filed (or as previously adjusted) with any other changes
you or your spouse are making
. If your spouse didn’t file an original
return, include your spouse’s income, deductions, credits, other taxes, etc.,
in the amounts you enter in column B.
Read the instructions for column C to figure the amounts to
enter in that column.
Both of you must sign and date Form 1040X."
CLICK
HERE for IRS information about Amended Returns
https://ttlc.intuit.com/replies/3300283
[Edited 02.25.2018 | 10:02 AM]
