Using Aim Offsets from variables

Hi,
I would like to use Aim Offsets to handle character’s attacks orientation.
I have some animation sets for different types of weapon. I want to switch Aim Offsets with for different sets. I prefere to store ref to asset in sets, like for an ordinaty Blend Spaces or Montages.
How can I use in Anim Graph a Aim Offset asset which is storing in a variable (Struct) as reference?

I can’t use it if I select “Blend Space as Pin”

Unfortunatly I can’t use child blueprints.