Thanks for the answer.
No, they're not managed after using Parceler, and that's the good thing, since then I can do stuff with the object without it being saved. For example, if I send object A to a dialog, and there you can modify the object, and the tap cancel/undo, and just close the dialog and nothing is saved to the database. And if you want to save, you just call CopyToReamOrUpdate.
So to be able to use temporary object, it's great. Since I don't want to add a lot of extra things to realm database, just to support undo/cancel.
So that's why I wanted to see if it's safe to just set the data for unmanaged objects and then at a later point, just call CopyToRealmOrUpdate. After thinking about it, then I don't see why there should be any problem..