Caregivers first
Greet parents and caregivers briefly first to get their endorsement so that the kids are more comfortable with talking to you. Let them know that you won’t be able to talk to them during the session, since you’ll be talking to their child or observing the session. After this is established, turn your full attention to the kid for the rest of the session.
Why this technique
Kids look to their parents to figure out if things are okay when they’re in a new situation. By acknowledging the parents first and getting a friendly conversation flowing, kids are likely to be more at ease interacting with you. Just make sure that kids are not left out. Kids should feel like they’re the experts during the playtest, not their parents. Parents aren’t the participants!