For a total of three units being serviced by a 60 amp breaker. Right now the double oven is run from 240V, and I need to add a 240V circuit for the microwave oven (there is only a 110V there now)
No. Ovens should be on their own circuit. While you can put them on the same circuit and only use one at a time, having multiple High Amperage Draw Appliances on a circuit is not a good idea!
Just think about it...cake in one oven turkey in the other, then heating the gravy in the microwave would result in a trip to the circuit breaker panel to reset the breaker.
If the breaker and wiring match Gauge and Amperage(i.e. 12 gauge and 20 Amp Breaker) then having multiple Appliances of 20 Amp is fine....the breaker will do its Job and protect the wiring! If multiple draws are going on at same time...breaker might trip thereby preventing a house fire!
Always a better idea to have the Appliances on their own circuit...even if it is not required by code. Especially these days with heater coils in dishwashers to heat and sanitize the dishes.....and large 36 inch double ovens!