Non rev the same day as confirmed ticket

I've had a relative book me a paid for confirmed flight with United. The problem is i don't think i can make the flight. I don't want to pester my Uncle in to changing the flight and him incur charges etc. I am an LH (Lufthansa) employee and there is a flight later that day with them Id like to take. This would mean going standby, which isn't a problem in terms of loads as its wide open. In LH policy it states you cant book a standby ticket with them on the same day you have a confirmed ticket with an airline. This is seen as trying to guarantee a seat by hedging your bets. From my side i cant really see a problem as United still receive my payment and i don't even fly with them. Can anyone shed any light on this policy, such as do they only mean booking a standby on the same flight or the same day or the same route? Can i book the next day ? Also if i did proceed with this how would LH know? Obviously i don't want to break any rules or policies as i am grateful for these privileges we receive. If doing this was a violation, i simply wont do it and find another way. Any help would be gratefully received. Thanks.

My suggestion would be to attempt a same day change with UA rather than take the risk with your flight benefits.

If this is a domestic flight within the US, Puerto Rico or the Virgin islands, UA as well as other US majors just announced they are eliminating change fees. Won't work for international. Not worth the risk of losing your benefits. Most airlines have rules against this practice.