I have alters who have historically prevented me from CTB. One believes we already died from a past attempt and that we're now some immortal zombie or something, and others come in and stop me or whichever one of us is attempting. Does anyone have any advice on how to make sure this doesn't happen?
I've had similar problems in the past. The issue is, it took me a while to convince my alters that this was the best course of action. If you have ways of speaking to them, because I know there sometimes can be a block, you can try discuss it with them and try and come to a solution all of you are happy with (the 3 years extra life we negotiated recently expired so I'm finally sure that I can CTB without anyone stealing the front and preventing me).
Another option, that I have tried, and it hasn't turned out really effective and just caused a lot of extra pain in the process, is to try force dormancy. The issue is, they will fight back. And trying to force dormancy / integration tends to cause a lot of shutdowns and flashbacks, especially if the alter you're forcing out is a trauma holder. Also, it doesn't tend to be that effective. They usually pop up again once I get really distressed and they steal front and I lose access to my body for the next few weeks or months. If you feel you can handle this, it can be an option, but it can also have disastrous impacts on your life.
Another option is to try get fully integrated in therapy. I understand that some of us can't wait that long.
I'm sorry. Being a suicidal system is... challenging to say the least. You can't ever be taken seriously, no matter how hard you try because there is always something blocking you, be it an alter, or society itself.
I wish you all the best. I hope everything turns out okay. And hey, you never know, maybe your alters can help you find a way to live with yourself. You just have to try communicate.