I don't think that you can raise the fry without Rotifers I've done some research and I've been raising my clownfish fry successfully with Rotifers for about a month and a half now.
Baby brine shrimps even when first hatched are too big for the tiny larvae and not nutritious enough anyway.
From my experience I've been more successful with much better survival rate when I feed Rotifers for at least 10 to 14 days before introducing Baby Brine Shrimps but you can start giving them brine shrimps at day 7.
So I really think that what ever vitamins and nutrients they get from Rotifers they can't get it from Baby brine shrimps.
If you can figure out how to get Rotifers sent to you (did you try eBay?) this step by step guide helped me a lot: http://www.fellsman.se/akvarium/raising_clownfish.pdf
It's very well explained and very detailed.
Good luck
There are copepods that are as small as rotifers that can be used. Rotifers are mainly used because they multiply quickly and they can digest nanno phyto. Other copepods like parvo require brown phyto.