Running more parallel lightweight threads/pr​ocesses/fu​nctions than available workers

Parallel computing question: What architectural approaches are available in MATLAB when the number of desired parallel processes exceeds the number of workers allowed in a parallel pool? I'd like to setup a flexible set of signal processing chains for post processing raw radar data (no real-time requirements). I have multiple streams (channels) of incoming raw data packetized into messages by each radar transmission event. Each stream needs to pass through a multi-step signal processing chain where the output of one step feeds the input of one or more others. Each source stream needs to go through a different progression of steps. Some processing steps need to collect input messages from multiple sources. I envision a config file defining all the processors that are needed and identify which source streams they need as input and which output streams they will produce. This is a classic publish/subscribe network. Perhaps there is a master process the instantiates and registers the processors and passes the messages between them. I also envision the processors are continuously running, waiting for a next message to process. One reason for this approach is that some steps may require multiple messages from one or more source streams before they can produce an output message (simplistic example would be a sliding median over N-events). Access to a stream's history could enable this, but would be inefficient. Perhaps a class object with storage and the processor as a method would work, or a function with persistent memory. The problem I'm having is understanding how to get this to work within the confines of MATLAB's parallel processing construct when the total number of signal processor elements is far greater than the number of workers allowed in a parallel pool. They are individually lightweight processes, but I need a lot of them running in parallel and preferrably utilizing the resources of my computer efficiently. Broad stroke solution approaches are welcome.