3 connectors and 1 domain

What way to choose in this case:
I have 3 connectors (for example three different active directory connections). They have three different domains (home realm discovery)

  1. test.com
  2. went.com
  3. other.com

I have a user that has email user@test.com and was connecting to the connector number 1. But he migrated to the second company with an old email. Now he would like to connect to a second connector using the domain test.com . How can I do it?