Connect 2 Products

Hey,
how can i connect two products.
I have a shop for relacing Baseball Gloves.
On that site i sell Laces solo and i am relacing gloves. How can i connect the Laces with the relacing.
Example: Some one orders a relacing with red laces. How can i make it that the stock changes the stock value of the solo laces without me changing it manual?

Thanks for an answer.

p.s. sorry for my english im from germany.