Possibility of breaking a complicated Activiti diagram in smaller units

[Puneett Jain]

I am writing a workflow for contract approval. Workflow diagram has become very complicated and I need to break it up but it does not seem possible.
For e.g. approval process goes through few departments in parallel and other departments can be invited by anyone. ANy department can add documents at any point. So I can't make each department process as a subprocess because it affects overall process.
I know I am throwing a random question but any ideas might be of help.
I have attached the initial workflow diagram. This is about 60% complete and not perfect fo course.

Thanks
Puneet