Disabled person trust

An old pre-2006 disabled person settlor interested discretionary trust. The settlor is treated for iht as having an interest in possession. Does this mean s80 will apply, ie it is treated as a separate settlement for iht (except in relation to the date of the 10 year charge) created by the settlor on death, so the deceased’s lifetime gifts are taken into account, and other trusts in the Will are related?

Simon Northcott