I was told there is a priority for first vs rear of aircraft, but the gate agents pretty much do what they want otherwise. IMO, they do what they want with their friends period. Keep reporting exact details to CPO. Write someone. I've written everyone for years asking for some kind of priority vs the vague guidelines we have. One of my personal experiences we checked in as S2 and were number 2/3. The person #1 changed S2 to S3 and we were now number 1&2 on the list: put on opposite sides of the jet, center seats, rear of a 757. The new number 3 got EC. Wife of a jumpseater "schmoozing" the gate agent got EC. Agent proceeded to board the jet in almost exact reverse seniority order with Buddies and S4 sitting next to each other close to front, aisle, window. Reported to CPO and pass people: I bet them the person changed to S3 and put in EC was a fellow gate agent. No takers on the bet. Nada, zip happened. Call station manager and keep complaining. Maybe eventually they will simply board us with some respect for seniority. OFG