Using someone´s eidolon as a mount

[Targutai Minyatur]

Lets supose im a barbarian and i want to use my partner´s eidolon/animal companion as a mount and he is trained to do so, how is the charging action? we charge together and the eidolon/animal companion makes his attack and so do i? that is in the same round?

[Targutai Minyatur]

One more thing, can a eidolon ride someone´s animal companion? (this time beeing the rider)

[Bard-Sader]

for ease of play, I would suggest that the barbarian delays his initiative so that him and the eidolon go at the same time. That way, you can both both attack the same target witt he same charge, at the same time.

And yes, as long as the eidolon has a shape capable of riding the mount, there's nothing saying it can't.