Hi Lalit,
Thanks for your update.
1. I feel sorry that there is no official schematics/white paper about this specific scenario currently.
2. At present, there is no official release about this, either.
About deploying DirSync and SSO for multiple forests environment, this is not a Microsoft supported scenario currently. I hope to be able to share an update in the near future. Thanks for your patience and efforts.
Thanks,
Young Yang