Dude: You're better off using Model Groups. Design Options are absolute rubbish for MEP designers/engineers. Most of the time, a full Duct, Electrical, or Piping system comprises all components of a system throughout the entire building. If you have an alternate bid item, or some other design option, in order to make it "work" you really need to just copy the ENTIRE system/model elements/etc into their own design option. This would be a nightmare to manage. A NIGHTMARE. Because If you have say, one or two boilers that both need piping and electrical systems connected to them in a particular alternate bid... in order for the "design option" to work correctly, you'd have to make a copy of the entire model to show the alternate. Now imagine doing routine design changes (oh let's route this pipe here instead) and trying to replicate that in 2-3 different design options. Nightmarish stuff. In Revit 2013 specifically, you can create systems, and you can add models to design options, and those systems wills till work. BUT. Once an item is in a design option... you can't connect it up with any main-model equipment. TL;DR: **** design options for anything but the most basic of stuff. Once you really get into modeling duct systems and electrical distribution systems, they are to be avoided like the plague.
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