I have a complex itinerary that includes the following segments:

YVR-ORD on UA
18 hour layover
ORD-LHR on UA
3 hour layover
LHR-ZRH on LY (codeshare)

At time of booking a applied a GPU to the ORD-LHR flight. This did not push the YVR-ORD into an 'upgrade requested' category, but since there was no R space on this leg, I didn't follow up.

Now there is R space on the YVR-ORD leg and I wonder whether the GPU that got the ORD-LHR upgrade could also be applied to the YRV-ORD leg?

Thoughts, and strategies on how to get this done on the phone (or otherwise) would be welcomed.