Can passholders purchase multi-pass for a park without a reservation?

Is this allowed? We'd like to purchase multi-pass for MK but rope-drop EPCOT and thus make our reservation at EPCOT. Will we be able to purchase mutli-pass for MK? Regular ticket holders don't need a reservation so it would be strange if the multi-pass system is checking for this prior to allowing payment. Another concern is that purchasing multi-pass locks you out of other parks until you visit the park you've purchased multi-pass for. I called member services and they couldn't say definitively. Has anyone done this or know if it will work?