Fantasy companions may be very good or horrendously bad. Sometimes these fantasy friends are blamed for the child's own acts. This is normal, not pathological. For one thing, a child can find out easily what parents will allow by having an imaginary friend do something. A parent should say what he would do if sometime he found the child herself being naughty like that.
Many children also try out lying and stealing to see what happens.
Of course, such behavior should not go uncorrected, but it is a mistake to interpret it as an indication of a future problem. The period approaching the start of regular school is one of introspection and attempts to understand the meaning of the child's own achievements. Their questions become ever more difficult to answer. By the time children have fully mastered the use of a spoon and cup, it is appropriate to move them from the high chair to a chair with the family at the dining table. This usually happens sometime at age 3 or 4, and the transition is likely to cause some disruption in family mealtimes.