I am amending my status from married separate to married joint filing, and it says my daughter doesn't qualify as a dependent bc someone else can claim my husband - fix?

[retiree]

If someone else (incorrectly) used the SSN’s you cannot e-file.  Your only option is to PRINT and MAIL your return, and let the IRS sort out the issued.  They will contact you and the other party and determine who is entitled to file.

When mailing your return it is best to go to the Post Office and send it Certified with Return Receipt.