It´s not exactly what I´m looking for because it doesn´t change the stock of the product with the same first variable.
for example:
“the main product name”
-lenght: 3.0m -mounting: attached to a wall
-lenght: 3.0m -mounting: pole, size 7*7*7
-lenght: 3.0m -mounting: pole, size 10*10*10
-lenght: 4.0m -mounting: attached to a wall
-lenght: 4.0m -mounting: pole, size 7*7*7
-lenght: 4.0m -mounting: pole, size 10*10*10
so if the costumer buys one of the fences, every stock of a fence with the same length has to go -1, and the costumer needs to see it on the front-end so they know that a specific fence size is out of stock.
Thank you for your answer, but it’s not exactly what I’m looking for. Because my client has products with at least 4 variations and what he asks from me is to make 2 groups of variation. So if my client buys one fence of a specific size and a specific wall mount, the stock of the fence with the same size but a different wall mount also goes -1
