Do they ever actually join your group aside from the mission quests? The Tips says they do but ive done 6 new game +s now and they havent actually joined the party, am i missing something or do i need to keep characters from last playthrough have them all be clone units in order to get them or what?

Have you tried keeping characters from the last playthrough? I don't know if that's the requirement 'm only on my first NG+ playthrough) but I would think it's worth a try.

They all seem to be marked as Clone Units if i do that, so im not sure, i would think if it were, they would mention that in the Tips section but who knows.

Considering Roka has to go off and fight some war and Lyphia/Evelyn go back to their inn, I'm confident that you can only have them as clone characters.

Wouldn't make much sense storyline wise if they stayed with your party imo.

how to unlock lyphia/evelyn? i did quest 106 - spatial rift, which u had to kill queen of souls, but it won't show up no matter how many monsters i slay, and those pesky banshee souls keep respawning like hell, is it a bug or something? i got the newest append and english patch also btw.

thx b4.

To get them, I think you need to have them successfully leave (if you keep advancing on their event points, it happen eventually) during the fight against the queen of souls, then do their(s) quest(s), that can sometime be tricky because of the need of installing the outdoor bath (I don't remember the proper name) at some point.
Once you complete all their quests, they become available on the next playthrough (like Roka).

i seem to be having this same problem. i don't have any trouble unlocking any other NG+ heroine but on my third playthrough (roka was supposed to be unlocked on the second one and when i started a new game.) i went through her shipwreck quest again on my third playthrough and shes still not unlocked its just a clone unit. Do i have to do the letters first? or is there some other issue? i haven't gotten to evelyn and lyphia's quests yet in this playthrough so i can't say for sure about them. But i have a feeling it might end up being the same way. Since im a Completist (not a word i know but you get the idea) I need these Three. Any assistance or help i can get with this will be much appreciated.

Roka and L&E are only available as Clone Units. Deal with it.

Could explain me what exactly is their role in other Eushully games? I have heard that Roka has some importance in Ikusa Megami games, but not much else.