NEW YORK (Money) -- QUESTION: We have many children in our family, and our children have many friends. Often their friends are visitors in our home, and it's not unusual for one or more of them to wind up coming along when our family goes out to a movie, the skating rink or a casual meal. Are we wrong to expect these kids' parents to chip in for such excursions? Just with the snacks, this is getting very expensive.

ANSWER: If you invite -- however indirectly or reluctantly -- one of your children's friends to join you in a family activity, the child is your guest and shouldn't be expected to pay.

Money Magazine's ethicists are consultants who advise attorneys on people's ethical beliefs. E-mail them at right_thing@moneymail.com.

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That doesn't mean the child's parents have no responsibility, however. On the contrary, if you're picking up the tab with any regularity, they have an obligation to reciprocate your hospitality and generosity, or to insist that their child pay his own way.

Parents also have an obligation to teach their children that, while accepting a small treat or two from their hosts is fine, asking for a large popcorn, a candy bar and a soda isn't.

"Show consideration for other people's pocketbooks" may not rank with, say, "Always tell the truth" as a guiding principle, but no one should pass puberty without having grasped it.

All of this said, maybe there's a simpler solution to your immediate problem than counting on your kids' friends' parents to do the right thing. Remember: It's perfectly okay to send a visiting child home when your family decides to go out.

So should the expense start to outweigh the pleasure of your children's friends' company, stop inviting them to come along.

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