Congrats!!!! Sorry I'm of no help with dogs in weddings (still waiting for my wedding day, lol) but someone on the aussie board on LJ had their Aussie in their wedding just recently. I remember they offered some advice, and I am sure if you contact them they would be more than happy to help you out.

You have plenty of time to train your 2 to obey well & the like. I wish yous the very best of luck with your future!