First step: When a person is ready to look, healing can happen. I recommend 9 weeks of path clothing. If and how then the twin shows up, or another theme lies over it, shows up step by step.

The second step to healing is to connect with the twin(s) and give it a name(s). ( I bought a big teddy that I fell asleep with almost every night for 2 years. )

The third step is to be aware that you were born alone because you chose it. This is okay and it may and should be so.