There are several questions with the PM=Sarah Stanton theory.
1. When did Stanton move to that corner?
If it was before Frazier, Williams and Shelley occupy the top landing then its plausible.
If Stanton remains with Sanders , however until the landing becomes crowded with the presence of Frazier, Williams, Shelley, then it’s less plausible she would try to squeeze thru.
2. What about Billy Lovelady’s WC statement “beside me” when describing where Stanton was in relation to himself?
PM was standing several feet behind Lovelady, so should not Lovelady have said “behind” me?
3. What about a statement that Mr Lovelady allegedly made regarding pointing out the person with hands raised shading her eyes in the Altgens 6 photo as being an office woman who worked on the 2nd floor office?
4. The object in the hand of PM could plausibly be a white coffee cup if PM were Stanton, however , would not such small quantity have been consumed in the 15 minutes prior to PM being seen in the Weigman film frames at 12:30pm?
5. Since a soda bottle appears to have been left coincidentally at the step where PM may have stepped down one step, and since the Hosty note suggests that Oswald had just purchased a coke before going out to watch the P.Parade, and since that quantity being 3x more approx than coffee cup , the probability (imo) is more in favor of PM=Oswald .
6. Since Stanton did not describe seeing Baker going up the steps , can this be rationalized if Stanton is on the east side of the hand rail (opposite Lovelady) as having been distracted?
7. If Stanton did leave “immediately” to return into the building, which is the more likely probable position from which to have done so? From the west corner where her way to the front door is blocked by several persons still on the landing, or from a position on the east steps?
7a. If she did leave immediately , should she not have seen Baker, Truly, and Oswald also as they all collide getting into the lobby?