new plugin needed

I have just created a online shop for a client of mine, but i need your help with this: When customers checkout on my shop, they are required tu fill up the regular fields, and i want a new field called Unic ID.-that`s simple to do What i need: for example, when the customers enter in Unic ID field number 1, the order should be emailed to a specific email adress, enter 2, order is emailed at a specific email adress…. I dont know what to try so i can make it work. Do you think it can be done? Thank you very much for your answers!