Sharing objects across Java processes-Collection of common programming errors

You can expose a service to allow access to the data from the object. It’s comparatively simple to set up inter-process communication using RMI. There’s going to be an IPC overhead so this will not be as performant as local access, fine-grained access will get expensive, but if you’re getting summary or other agregated data then this could be a decent model.

You don’t say why these are separate processes. Do you have any opportunity to load the code of you child process directly into the parent? Dynamic loading and unloading is possible.