Yeah, try double boiling them. I would use some of that in the boil, but I would then also consider melting them down again and using that as my priming solution.
I provide info on priming with alternative primers including fruit juice (including the link to the podcast,) and other sugars in my bottling stickey- Scroll to the lower half of
this post.
It will show you how to figure out how much you need based on any nutritional info you can find, on the amount of actual sugar in them.