Not necessary DT1 must include you to become DT2, numbers of DT2 can include you to become a DT2 also.
This is wrong. You can't be a DT member if you are not in trust list of any DT1 member.
For being a DT2 member, you need to be in trust list of at least 1 DT1 member and the number of DT1 members who have included you in their trust list must be bigger or equal to number of users who have excluded you from their trust list.
Oooh. I never knew that.
I always thought any DT2 that is included in DT1 can add you to their trust list and multiples of this can turn the person to automatically another DT2.
Thank you.