Hi Holly,
I make that judgment by territorial behaviour I see.  I first had one group
of five consisting of one older male dominant, a younger male, and three
females.  Then another group arrived, one male four females. The behaviour
patterns, territorial and flight chase, brings me to the judgment that they
are two distinct families.  The two groups arrive in a group together, and
leave in the group; they also head into different directions when they leave.
I see one group everyday, the other group arrives periodically, but
frequently.  The two groups also take their seeds to different sections of
the white pines at the corner of my house.  If your chickadees are together
it is very likely they are related as chickadess and, as well as titmice
flock by families in the winter; as the winter wears down you will begin to
see territorial displays as "courtship" begins  I also see that when the
whole flock of goldfinches, nuthatches and chickadees are feeding and then
all take flight in a "safety" rush, there is one particular male chickadee
who returns to the feeders before any other bird, then the other birds begin
returning, first one then another then another, then they seem to "fall" from
the trees around the house.  He also comes and watches me when I fill the
feeders, he will sit on a branch sometime ten inches from me.  I do love
those little birds.  Did you know they store seed as the nuthatches do?
A male Hair and male Downy have appeared now too.  It seems that the male
goldfinches are getting brighter.
I've started seeing some female cardinals, four, then four, then two.
These are just my observations--hope they help.
Kathryne Silberman
Chelsea