Handling slackers
Convert the conversation
If you really are a team, your job is to help your team members, not tell them what to do.
Instead of telling them what to do, help them make a plan. Consider how this kind of approach might be better received:
Billy, you're falling behind on points. Let's figure out a plan to catch up. What would you like to do?
Call out opportunities
Don't be afraid to call out opportunities to your slackers.
Perhaps there are some high value chores that would let Billy quickly catch up. Or, perhaps he can snatch some easy chores before his sister gets home, and she grabs them.
Billy won't resent it, because it's his choice. You're just pointing out opportunities.
Some people like to chip away every day. Some people procrastinate. The early birds will get their pick of the chores. The procrastinators will get the dregs.
The goal is for them to curse their own laziness, instead of your nagging.