I road home on Usair to CLT, and a CO-Pilot had something he could not wait to show me. Evidently a pilot at Usair has gotten ahold of our seniority list, and has created a combined Usair/AA list that shows them where the will fall with strait date of Hire. This is the second trip in a row to clt on Usair where the co-pilots are obnoxious about date of hire. They are also up set that APA accepted pref bidding, and want there current system to remain. On both trips home the Co-pilots were upper 50's maybe even 60. I don"t really no the details of what we are doing about this subject,but their tone is a little nasty/demanding. They are deathly afriad we a going to take over, and they will be marginalized(YEPH). I can only hope the Fence is sufficently high to keep us from being over run by this Geriatric mob!! (The capt had 27 year's, and was about to be displaced to Co-pilot on the A321.)Danm!!!!!!