If you have no family tree on FTDNA the tool will not work and you will
have all your matches bundled together rather than separated by maternal
When you test both your parents the system will know who sits where
between maternal and paternal. As most people don't have both parents to
test, the more close relatives you assign in your FTDNA family tree, the
easier it will be for the algorithm to phase your DNA between maternal
and paternal. This is because each close relative has the potential to
contribute with different segments of DNA.
The person who assigns test results to individuals on a family tree is
the owner of the profile and the family tree. If I know a maternal 2nd
cousin tested, I will assign his/her results to him/her on my FTDNA
family tree. Of course, I must know the branch in which this individual
sits, otherwise I will be misleading the system.
Hope this helps,
Rio de Janeiro, Brazil