Answered
Link layers so when one is changed, the other changes to match it
I have certain Fancy Designs that only work with certain others.
Is it possible to link layers so that if a customer selects a different design, a second one will also change if necessary?
That is currently only possible within FPD with colors (color-link). The only other way of doing something similar this would be to use WooCommerce variations: http://support.fancyproductdesigner.com/solution/articles/13000032251-using-woocommerce-variations-to-change-the-fancy-product-in-the-designer
Ok thanks that's a start. I've set that up, but it does not solve the full issue. I'm making a separate post because I don't know how to link specific design categories to specific variations.