How to trade between 2 sprites of the same type?

Hello !
I am making an economic simulation, with different building trading with each other.
So basically, at a moment, I need to pick two of them and transfer goods and money from one to the other.

However, in the event system, I don’t see any way to select 2 objects of the same type, and give them different roles (the buyer, the seller). Is there any easy way to do that ?