We sell yarn, 5 different types. We also sell patterns, which call for specific types of yarn.

So we have a main category of yarn with the five different types listed:

Yarns
product 1
product 2
product 3

And we have a main category of patterns, with subcategory for pattern types:
Patterns
Sweaters
pattern 1
pattern 2
pattern 3

Hats
pattern 1
pattern 2
pattern 3

You get the idea.

Now, we've had requests from customers to browse for patterns by the type of yarn required by each pattern (that's right, you can't knit a hat from just any old yarn). We've considered setting up a new category/subcategory tree:

Patterns by yarn type
Yarn 1
Sweaters
pattern 1
pattern 2

But it's awfully time consuming. Is there a better way? An addon of some sort?

Thanks,

John