hi i am a new owner of 3 Garter Snakes i think they are apart of a family because when i caught them they were all in the same burrow/hiding area

the 2 older snakes (Adult and Adolescent) seem to like each other a lot in fact the smaller adolescent garter is always on top of the adult and is pulsing on it especially near the back of the tail, is this a sign of breeding?

please help

BeardedIggy