[@Banana]

Eos isn't dumb, she knows who Miyu is and what she's capable of very, very well. The simple fact that she can admit people like Miyu, Henry and Fran to join the Machina defies logic, but can be done for the story's sake.

Nevertheless, none of them can ever expect any form of decent treatment if they don't work very hard to prove themselves (and even then, Eos might still keep the remote termination button at hand at all times). The fact that Bonesword hasn't received any rewards is based this very argument, he hasn't proven himself yet and likely will take more time (he run away from Arcadia for no reason!).

They can join, but until they prove to not be a threat to the Machina, they'll be treated as 3rd class individuals and potential betrayers/spies. You can't really ask for more.