Cat group a threshold

I see that the group A disponer/beneficiary threshold is €434,000 from a parent to a child.

Revenue say that a parent taking an inheritance from a child may qualify for the group A threshold.

In what circumstances would a parent inheriting from a child fall in to group A ?

I am wondering what happens where the disponer is an adult wishing to leave a legacy to an adult benificiary.

The child dies but has previously received at least 1 taxable benefit from the parent in the 5 years prior to death- to be taxable, the benefit must be a gift worth at least €3,001. there won't actually be any tax payable due to the threshold but the €1 is 'theoretically taxable'.

An inheritance arises when a person leaves assets in a will to another on his/her death. If a son/daughter leaves assets to his/her parents by a will then the parent will be granted a group A threshold if the child dies. If the parent were to receive a gift from the son/daughter (ie the son/daughter doen't die) , that would be a group B threshold.

Thanks for the information deadlyduck.