The only way you can go back in and add the 1099-Misc. is if your e-filed return was rejected. If your return was accepted, you will need to file an amended return to add the late received 1099. Don't worry as this is NOT an audit trigger by any means. If it was accepted, just wait until your original is processed and settled. After the return is processed and you have paid or got your refund, simply file the amended return and add your wife's additional 1099. I will give you the amendment link below, but please note, the form and link will not be ready until later this month.
https://ttlc.intuit.com/replies/3288565
