Hi,
Tshirt is with only selected book so for example book A comes with Free Tshirt A and book B comes with Free Tshirt B
There are no sizes option as of now they are all L size so I am not worried about it.
I still can't figure out how to add a free product with any product?
In a Nutshell if customer purchases Book A free Tshirt with price 0 should be added (no options in Tshirt).