I wouldn't recommend putting relays in that interface arena. Mechanical switching heavy loads is an emi nightmare. Kind of like putting a blindfold on and walking through busy streets, and hoping everybody will avoid you. Why would you do something that potentially will cause step insertion or loss issues and ruin a part. Put the relays away from open logic signals and wiring. Thats what the aux channels are for, to drive relays off the board. And preferably use a ZERO crossing SSR to switch ac signals.