Relatively new to booking with UA miles.

I'm looking to go STL - FRA
When I use the UA WEB site I see I can get a non-stop from ORD - FRA on LH.
That works.

I also see there are flights that go from STL - ORD that get me into ORD in plenty of time for the international flight.
That works.

When I enter in STL - FRA it never gives me the STL - ORD - FRA routing. Is this something I could call in and ask them to route the flights that I am seeing or am I stuck with the routing the WEB site gives me?
Thanks