Companion awards mixed with other star partners than allowed on companion award.
Yesterday I made a booking with LH from STR through FRA to IAD and then connecting on UA to xxx.
My ticket for the whole trip costs 140K - iget my wife to IAD on the companion award for 70K and need to get an award on UA from IAD to xxx.
(Or alternatively purchase a tix for those segments = IAD-xxx-IAD).
So yes - it is combineable = companioable for the segments that are on LH or its associates metal - whilst the issuer can use his trip as a regular staraward as per my example.
I have done similar to DPS - companion award to SIN with my award ticketed all the way to DPS and for my wife a seperate award in addition for the return SIN- DPS.
Cheers
Thomas