Please have the SDKs allow to copy objects from one partition to another. Currently you have to manually do it, which isn't great but not horrible, until your object has nested Objects, List<>s or EmbeddedObjects (via referenced 'foreign_key' / _id) - that is when it gets nasty and cumbersome. In Legacy Realm when ever you copied a top-level object its nested Objects & List<>s were copied automatically. That is not the case anymore, in MongoDB's Realm each one has to be done manually.

Built-in deep copying Objects is further important since:
1) Using partition-based Realm leads to denormalizing your data, which means more copies (not horribly bad if a new object but if existing one then harder).
2) Another reason why you need to denormalize your data is that Sync Permissions are determined at the partition-level, and not at the document level. It would have been nice to be able to use the ‘%%root’ as a JSON expression in Sync Permissions (and process are document level) to gain access to each document (aka: object) being processed - in order to allow / restrictions read or write permissions.