Success using multiple devices with Overbridge and Pro Tools?

Has anyone gotten Overbridge to communicate with Pro Tools using multiple devices? I can get my Rytm and A4 to communicate individually but not together as an aggregate interface. Has anyone experienced this or might know of a work around?

i cant test as i only have a rytm that works over OB. however i think rytm (mk1) only does 48khz so it might be that you need to have both devices set to 48khz or make sure you set it to be masterclock.