hello all how are you? i am in an Alliance and one member is in DEN so i made a flight from my hub to den and have like 23 or 25 pax on a plane that has 183 i know that i can downgrade to a small ac but none of thoes pax are conectin to any flight… i though when i join an Alliance it like a IL agreement am i right thanks for your help 
That’s a wrong assumption. You still have to sign an interline agreement with the respective airline, otherwise passengers won’t be able to connect.
ok thanks so what the advatige of being a part of an Alliance?
At the moment, just have a discussion board.
Alliance can decide to somewhat implement their own rules. For ex, they may decide to have exclusive IL agreements with their members so members of your alliance do not interline with your competitors. But of course, you must still pay the IL cost.