We need to change/increase the price of a variable product, when an attribute with a certain name/slug is used inside the variation. For example, when a T-Shirt has the color "White", we want to increase the variable product price by 3$.
So:
Color: White | Size: L => +3$
Color: Blue | Size: L => // do nothing ...
Due to our product stock and settings, we need to achive that with a function placed inside the functions.php
Thanks for help, Sirc