I believe that you will need to give the Right to Rescind notice.
I’m guessing you were having some questions as to if you needed to look at this as a refinance of a first or junior mortgage. If you look at it as being a refinance of a first lien; well it’s not with the same lender and I assume you do have new funds since you are paying off the first mortgage. Both items would cause you to have to disclose (assuming it is consumer purpose).
If you look at it as being a refinance of a junior lien, then if it’s with the original lender and no new funds and consumer purpose then you would not have to worry about the right to rescind notice. That being said it really sounds like you are extending new funds with the payoff of the first lien. If that’s the case then you will need to give the Right to Rescind notice.