@Tommyleedoggy
My personal opinion is that the note is unnecessary, and may actually delay your tax refund even longer. The IRS’s normal procedure when they receive a mailed in return that lists a dependent who was already claimed on a previous return, is to process and pay the mailed in return as-is. It then takes about nine months for the IRS to start a formal investigation of the duplicate dependent claim. By that time, your mother‘s amended return will have been received and processed, so the computer won’t actually have a conflict to resolve.
Mailed in attachments that are not part of a standard tax return can get lost, and there is no guarantee that even if it is scanned into the system, that a human being will read it for several months. But if a human being does read it right away, it may delay your return more than usual.
My suggestion is to simply mail a correct tax return with all required attachments, but nothing extra, and wait to see if the IRS or your state wants further information. However, other experts may have different opinions.
