I do not have experience working with combination devices, but several of the posts above mentioned the option of submitting an RFD, so I did some research on this topic to see if it is as easy as it sounds. In one article I found, the author mentioned that between 2009-2014, 67 RFDs were submitted to FDA, and 69% of them were found to have insufficient information provided by the sponsor. The biggest deficiency found was that companies failed to distinguish between the primary mode of action and multiple modes of action with reasonable certainty. So although it sounds relatively easy to submit an RFD and just let the FDA decide what regulatory center is responsible for the device, it appears that many companies fail to provide adequate information for FDA to make that decision.