Etherians are even more clueless than the Eternians
Every time Adam came to visit Etheria, He-Man shows up.
She-Ra called He-Man brother in front of them many times.
(where He-Man introduced She-Ra to Man-At-Arms and Teela as his "friend"...at least he was trying to conceal their secret)
Adora shows up to join the rebellion the same time She-Ra enters the scene.
Shadow Weaver and Hordak knew that Adora's sword was causing her to resist their spells of control...the same jewelled sword She-Ra has? (I know Adam had a sword just like He-Mans but the jewel in She-Ra's made it a bit more recognizable).
Adora tells Glimmer that she and Adam will go and rescue her mother Queen Angella in Secret of The Sword...but they return with her as He-Man and She-Ra.
I know...it's a cartoon...willing suspension of disbelief and all that but it was still kind of amusing.