I have big doubts about Freddie Mercury, but for the other two I would like to have an opinion from you. The cut out from a press map was supposedely signed by McCartney 1989 in Hamburg.
The Santana sig is from the gatefold inside of an Amigos vinyl.
Maybe you remember that I mailed a couple of Bowie sigs from 2013 which were doubtful for you. I got them for free since the owner could not remember where he got them from....