If I'm understanding your question correctly it sounds like you need to create a base class for all actors that you want to reference this way.
For example say you had an Actor of type Chair, and an Actor of type Table, and you wanted to be able to access a variable that stores the Actors color. If you create a base Actor called Furniture that holds this color variable, you can extend child Actors from this blueprint to be able access the variable regardless of whether the target is a chair or a table or any other child of the base class.
To extend a blueprint from a base actor, simply right click on the blueprint you have created and select 'Create Child Blueprint Class' for each Actor you wish to access the variable from. The important thing is to make sure the variable is stored in the base Actor blueprint, and not the child blueprints.