In {HEAD ~ addition} to {TAIL ~ the master calendar}, a user may add secondary calendars in the present invention 
to
In { HEAD ~ addition } to { TAIL ~ the master calendar } , a user may add secondary calendars in the present invention
OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH