I got the following from another BOLer. It's been a while back and I don't remember which one so I can't give proper credit. Also, there is no warranty for its legitimacy.
ADDENDUM to Your Right to Cancel
We have agreed to establish an open-end credit account for you, and you have agreed to give us a security interest in your home as security for the account. The terms of the agreement allow subsequent advances on your account when the amount borrowed is less than the credit line. You have a legal right under federal law to cancel the right to make subsequent advances on your account, without cost, within three business days after the latest of the following events:
(A) the date of the opening of your account which is ______________; or
(B) the date you received your Truth-in-Lending disclosures; or
(C) the date you received this notice of your right to cancel the right to make subsequent advances on your account.
If you cancel the right to make subsequent advances on your account, your cancellation will only apply to subsequent advances. It will not affect the amount advanced for the purpose of purchasing your home when the account is opened, and it will not affect the security interest we have in your home. Within 20 calendar days after we receive your notice of cancellation, we must take the necessary steps to reflect the fact that your home does not secure subsequent advances on your account, and we must return any money you have given to us or to anyone else in connection with any subsequent advances.
I hereby acknowledge receipt of two (2) copies of this addendum. Should I decide to cancel my right to subsequent advances, I shall do so by midnight of _____________________ by sending a copy of the Notice of Right to Cancel along with a copy of this addendum to the address specified on the Notice of Right to Cancel.
_____________________________________ ________________
Date
_____________________________________ ________________
Date
_________________________
The opinions expressed are mine and they are not to be taken as legal advice.