Have (2) June-July MIA-MAD-BOS (<--2:30P) as AA busn award;
(was lucky to find these just week ago, MIA-MAD-MIA award was unavailable)
so now am awaiting (2) BOS-MIA Avios award seats to appear,
probably ~14 days before (MAD-MIA),BOS-MIA desired date, right?
There is BOS-MIA 5P n.s. best departure & BOS-MIA 7P n.s. second best;
it is possible 7P will become available as Avios 10K award one or more
days before 5P possibly does; BA rep said grabbing 7P n.s. & changing to
later appearing 5P n.s. will be free for only first 24 hrs, any longer =
$80/person --
is that correct?

(am booking BOS-MIA Avios award online to avoid $25 phone fee)
Can I keep reserving-cancelling 7P within 24 hrs,
noting #seats still available, as a way to "freely"
grab possible 5P award seats? Thanks in advance!