On the whole you would probably find yourself frustrated by the efforts of suppliers in China in conceptualizing and helping you to develop a range. Generally speaking Chinese suppliers are good at making a product to a price and in quantity but I would not rely upon them to understand your ideas here.

So to save yourself a lot of headaches you would really be best off to supply the manufacturer with completed mockups of what you want them to do. Outline colors, materials, stitch lines etc. Give them all of the details so that they can make what you want without having to guess.

Personally I think that some of these factories are VERY talented at getting the job done and getting it done well, they just seem to have a lot of trouble imgaining for themselves how to get it done.

So I would be sending samples and receiving samples for final confirmation of every detail before starting any production.

You can probably find some quite strong trading companies in Shanghai to help you handle this and act as a good go between for you and the factory.