You just do the equity release as a side loan which in most cases u should do anyway. That way you maintain discount on current lending.
This is for topup, yes, but I now have many subaccounts for each equity release, it become unmanageable. In Sydney, it's not uncommon to do topup/equity release every 6 months in the last 24months.. Not sure banks have view that there are too many accounts and it become costly for them to run/maintain , hence harder to provide the discretionary discounts.