I found this some time ago and it has been quite helpful -

In order to survive abuse, a young child has the ability to fragment her spirit into multiple parts. This is like freezing a lake and breaking off chunks of ice. Even though each chunk of ice appears separate, it is still part of the lake and still belongs in the lake. Just as the warmth of the sun melts chunks of ice back into a lake, the warmth of self-love invites each alter part back into its original place in the soul.

No matter how loving you are toward your alter parts, they can only remain separate by your choice to reject them as part of yourself. Once you accept that they are all You, there will no longer be a need to keep them separate, and they will naturally integrate. Integration does not 'kill' any part of your spirit. Instead, integration merges all of the parts back together. While you will experience those parts of yourself in different ways, they will still be a part of who you are.

Be patient. Most people do not succeed in staying integrated after their first attempt, so be patient with yourself.

As you master this skill you might find that you are staying integrated for longer periods of time. Celebrate your successes and be patient with the process.

You are using an enormous amount of energy to keep yourself compartmentalized. By allowing yourself to integrate, you will free up an enormous amount of energy that you can use to continue healing yourself.

Acknowledge that you are one person. Choosing to integrate can feel like being asked to give up a superpower.

For most of your life, you have not been 'alone' because you have had other parts for companionship. The reality is that you always were only one person. You did not have other people enduring the abuse with you. You faced the abuse alone and created alter parts to give yourself the illusion of having support. While this truth can be hard to accept, it is an important part of healing yourself.