title: Opencart how to related 2 options in a product
body: <p>Hello I have the following problem.</p>
  
  <p>I have a product with two different options, size and color. But I didn't know how to related this options when someone is buying a product. For example.
  I have 4 T-shirt on my inventory 
  2 Blue T-shirt size S
  1 Green T-shirt size L
  1 Yellow T-shirt size XL</p>
  
  <p>I configured the product with these requirement options (size and color), but for example a customer can buy a T-shirt size XL color blue and that's wrong because I didn't have a way to related the color with the size. Any Idea, plugin or suggestion???</p>
  
  <p>Thanks I'd appreciate your help.  </p>