Like you’ve notice, BDs and DVD are different in how the menus are set up and designed. In fact, you can’t really compare the 2 since they are completely different technologies. Dont let the fact they both end up on tiny flat discs fool you 🙂
I cant give you any tip or tricks on Encore but I can say its a very buggy and limited piece of software for BD. The titles you own weren’t done on Encore. Encore is fine for one offs for the client but its not something you want to be using if you plan on replicating 1000s of copies for retail.
Personally I think you should send this out of house to an individual or company that does BD work. You will also need to consider moving over to 1 of 3 tools to do the work: Do Studio, Scenarist or Blu Print. In a Nutshell, taking on the job of this BD project, if you plan to replicate or come close to the quality and functionality of store bought titles, will set you back $5K to 70K…..not to mention the weeks or months of getting over the learning curve and testing your workflows.
Here’s an article which goes over each:
https://magazine.creativecow.net/writer/eric-pautsch
I would get these books first to learn about the technology. You dont want to be doing work for a client without an understand of whats inside the BDMV folder youre providing.
https://www.amazon.com/Blu-ray-Disc-Demystified-Jim-Taylor/dp/0071590927/ref=sr_1_sc_1?s=books&ie=UTF8&qid=1328560288&sr=1-1-spell
https://www.amazon.com/High-Definition-DVD-Handbook-Producing-Blu-Ray/dp/0071485856/ref=sr_1_10?s=books&ie=UTF8&qid=1328560313&sr=1-10