Concatenate sub-process task flows (BPMN)

[Smartrek]

We’re modelling processes through several levels of detail according TeleManagement Forum’s Application Note GB921U. We model the processes in EA 7.5 with BPMN 1.1 notation. Our approach is to define sub-processes (level x) which are reusable in different business use cases. To each sub-process we assign the corresponding task flow (level x+1) as composite. After having modelled all required sub-processes we are free to build the required business use cases as a flow of sub-processes (level x).
What we would like to do is to generate a more detailed diagram showing the end-to-end task flow (level x+1) of a business use case based on its sub-process flow (as each sub-process "has" its task flow as composite). In other words we would like to concatenate the task flows of the sub-processes. Is there any possibility to do this in EA or with a dedicated plug-in or any reporting method?
Thank you for any suggestion.