If I have an itinerary with an upgraded segment, (ie, EWR-SFO-SIN-SFO-EWR) and one segment is upgraded (ie. SFO-SIN) and then I do a change via the UA site to an not yet upgraded segment, will it affect the preserve the upgrade? Does it make a difference if I change a segment on the same leg as the already upgraded segment (ie. EWR-SFO) vs changing the other let (ie SIN-SFO-EWR)?
Or is this something one should always call in?