I've a little problem with getting the right overview model when dealing with eEPC.

The background:
I've started to create a Business Process Landscape for the IT-department within my company.
There are some processes which have a logical hierarchy (timely) and there are also some , which can not be put in a hierarchy and this is the reason, why hierarchy diagrams or process decompositions were not the perfect solution.

Does anyone have an idea?
Thank you very much!