There is no problem in using single AppId in multiple applications - your approach is valid. You just have to specify it when using the Everlive instance in every mobile app that you create. There are no additional checks for the AppId that is being used in your hybrid app.
Just for your information you can also have more than one Everlive object in a single application and each object has access to different backend services project. This is controlled just by initializing every instance with different AppId.