Unfortunately, it appears that your current Web API does not enable users to upload new album track information. I work at the Ministry of Sound in London and we're currently looking into the possibility of programmatically uploading our new album data to Gracenote from the business application that we use to create the album data in. It presently exports to PPL, chart companies and our digital distributers and we'd love to be able to also export to Gracenote. With our high volume of releases, it would save us plenty of time.
I have spoken to Jon Meesam who said that he'd be prepared to write a C# wrapper of the relevant code from your GNSDK, but he wasn't sure if that would be ok with Gracenote and so, I'd like some clarification on that please.