Stamp duty - BTL but with a difference

[PH XKR]

Hi

my partner moved in a few years back and has been renting her existing property out for this time.

I own this house and her name is not yet on the deed.

We are looking to remortgage her property and add my name to the deeds and eventually hers to this.

Are we liable to the new 2nd home stamp duty? I know it may seem like a silly question but where I see this as exempt as it isn't a new purchase, it is just adding someone else to the deeds, does the filthy Gideon see it the same way?

Thanks

[PH XKR]

Sneaky buggers