Hello Nina11,
Sorry you've been having a tough time and all the best to you.
As for Indie, I've had some ideas, I don't know if they'll help but I thought it's worth throwing them at you.
You say Indie can't speak. Is it possible she can't use language (or just can't do it yet) therefore she's using vivid imagery to try to communicate with you? Or communicate her emotions?
(possible trigger warning?)
Perhaps whatever trauma happened to you it occurred before you too were able to use language to communicate and so, you had to endure it in silence.
(trigger warning end)
One thing I have to say is that perhaps the reason Indie appear is because you are in a better place to begin the healing process and get some answers. My partner's alters revealed themselves recently, and though they warned me she's not ready yet to hear her answers she's more ready than she ever was, and also ready to accept their presence.
Perhaps this is why Indie showed up.
I'm sorry it's so hard for you all right now, and I agree with the others that perhaps one of the alters you have will be able to communicate or look after her. As for new alters popping up, again, perhaps it's happening for a reason. If none of the pre-existing alters can help with Indie, perhaps one of the new ones can. My partner has a small and succinct system but everyone is there for a reason. Little J is likely the victim of the trauma, Nif was created to look after Little J and allowed my partner to toughen up, Janey is Little J's nurturer and is there perhaps also so that Nif wouldn't be alone, as she was by herself with the 5 year old for a really long time.
Whatever the case may be, don't be afraid, you have a support system, both inside and out. Work with what you've got. Try to talk to your alters about what you've been feeling.
I know all this is coming from someone who isn't a multiple so I can't speak from first hand experience, but I hope you find it helpful, at least on some level.
Best of luck to you all.