Hello! If you are a system needing advice/help or want to help someone who is a system you're in the right place!
I have been in the plural community for well over a decade and have a lot of advice to give newly discovered systems, if you have any questions I have not covered here you can contact me On Tumblr my askbox and messages are always open.
First of all, I am proud of you for taking this huge step in understanding yourself! It can be very scary to realize you aren't the only person in your body and you are not alone in this experience. Personally I felt relief in realizing that there was a community of people who have the same experience that I have lived with, and that is valid too!
I am going to list some common questions and problems that systems have and give some advice and resources based on my experiences as a system.
No. Contrary to popular belief, plurality is not caused specifically by trauma. There are types of plurality that exists without trauma, which are called Endogenic plurality. There is a lot of discourse surrounding whether or not Endogenic systems are valid or not, and I will likely be making another page on this site about that topic, but for the sake of this page my advice is: If someone says they are plural, I believe them regardless of trauma history. The type of plurality caused by trauma is called Traumagenic Plurality, and is the most well known form of plurality.
Dissociative Disorders are the most common forms of Traumagenic Plurality and are generally formed by trauma over time in childhood when you cope by dissociating. In our experience it does not matter how "severe" the trauma was, moreso how chronic the stress from it was and the lack of a safe adult to support you through it.
Whatever your experience was DO NOT DIG FOR REPRESSED TRAUMA WITHOUT SAFEGUARDS IN PLACE OR A PROFESSIONAL HELPING YOU if you do not remember something, there is likely a reason and it is likely for your safety. This is one of the reasons I don't place someones' validity on their trauma history. Part of the disorder is repressing trauma for stability and if you try to remember repressed memories before you are safe and ready, it can destabilize your system and cause many mental health issues.
This is why we fight against the concept that severe trauma is necessary for plurality, because that then led us to try to search for some major trauma in our past in order to be 'a valid system' and led to us creating false trauma memories of things that did not happen. It is a good idea to separate your identity from your trauma, and focus on other parts of your identity.
Not all systems have amnesia, especially not black-out amnesia. Most systems have a form of amnesia that does not have a name but is coloquially called "grey-out" amnesia or "dream-like" amnesia. It is a similar experience to when you are driving and forget the last stretch of road you drove, or like trying to remember a dream after you just woke up.
Many singlets (people who are not a system/plural) find the concept of amnesia terrifying, and to them it is. For many systems with amnesia it is just another part of life, they dont even question it or think that they are simply forgetful.
Personally I didn't even realize I had amnesia myself until someone told me that it isn't normal for someone to only remember information of the past and very few actual details without prompting them forward.
This is a more complicated issue, the simplest answer is "communicate with them." But, as with most issues, it is just a bit more complex than that.
Now that you know you aren't alone in your body, you need to begin to acknowledge that it is their body too. I will provide some communication resources, but in this case communicating with your headmates and finding a way for all of you to be able live your lives and share the body equitably.