By letting clients have creative control some surprising and deeply meaningful representations can occur. Sometimes clients will include deceased persons, pets, or technically unrelated persons. This is not a problem. Leave any omissions, or lapses, in place avoiding discussion about them until after the sculpture is complete. They contain a message.
Clients are often pretty creative in utilizing the immediate environment in their sculpture.
Keep in mind that any family sculpture is from the client's own unique perspective representing their interpretation of how the family exists in relation to them. Other family members may view the family as being of a much different configuration. In groups it is not uncommon for a few individuals to initially declare their disinterest in doing a sculpture of their own. However, by the end of the group everyone wants to sculpt their family and the group inevitably runs out of time. Family sculpting is usually a very popular group activity that lends itself to adaptation to a wide variety of group settings.