Here's a thought;
I think it is possible that the real intention of Martha Stroud's comment in the Stroud letter could well have been to discredit Vickie Adams, by making the point that, according to Garner, Truly and Baker came up after Adams went downstairs, when Adams herself had testified that she did not see or hear anybody on the stairs as she was coming down.
It backfired massively, of course, but it's food for thought nevertheless.