BIR advised to rescind EJS with Donation

Hi, Panyeros and Panyeras.!

First time to encounter this case. Handling this for my Tita 😅

She executed an Extra-Judicial Settlement with Donation (she donated her share of her husband’s estate to her children; notarized and accepted).

When she went to the Bureau of Internal Revenue, she saw the taxes (estate + donor’s tax) are very high, so she wanted to back out.

She says BIR told her to just rescind/cancel it, and that only she needs to sign.

Main question:
Can an already accepted donation (inside an EJS) be undone this way?

Also:
Is donor-only rescission enough?
Should a new EJS (no donation) be done after?

Thanks in advance for your help 🙏🏻