Why do you believe that the gathering occurs, "at some trump other than the last trump." When 1Cor 15:52 clearly states that it does?1 Thessalonians 4:17 Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
Rapture or not someone alive is caught up to meet the Lord in the air. The answer to the question then cannot be not, but when. It's evident or sufficient for me that it happens at some trump other than the last trump, and to then seek the when.
In the revelation of Jesus Christ by God to John, he sees different ones appear before the throne in heaven. Again they must fit the criterion of 1 Thessalonians 4:17, the dead in Christ first, and then them that are alive. If there is no catching up, just how do they get there?
1 Corinthians 15:52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.