V. weak sauce, Mr. Collins.........
Mrs. Rowland is not Mr. Rowland
Mr. Edwards is referring to a later point in time
Mr. Brennan is referring to a later point in time
Mrs. Rowland's testimony is relevant regardless of whether you like it or not. You cannot just dismiss it because "she isn't Mr. Rowland". She was with him at the time and discussed what he saw with him at that time.
Mr. Edwards time frame is only a few minutes later in time. What is significant is that he said he didn't see anyone on the fifth floor at that time. However we have solid evidence that there was three men looking out the fifth floor windows directly below the sniper's nest (and one set of windows west). It shows that if Mr. Edwards could be mistaken, then so could Mr. Rowland.
Mr Brennan said he arrived as the epileptic event was happening. And he said he observed the sniper in the window very soon afterward and well before the motorcade arrived. So, I don't think it was much later at all.