My 3yr old has a make believe family

My three year old has recently created a make believe family.  He has a "new" Mom, Dad, brothers, sisters, and pets.  He speaks of them often and will compare them to his real family at times.  He will also use his new family to try and get his way.  He will say things like "my new mom wants me to do..."  Or "my new mom dosen't want me to go to bed now."  Or "my new mom bought me..."  At first I thought this was a version of an imaginary friend, but it's beginning to frustrate the rest of the family.  Is this a normal childhood behavior or is there something he isn't getting from us that he has to make up a new family to get?  We were also wondering if his older sister having a father and a step-father active in her life may be a contributing factor to his "new family"?

[Kevin Kennedy, Ph.D.]

Dear Roger,

I can't know, of course, if your son's older sister's situation is having an influence on him. Whatever the case, the behavior is not outside the norm for his age. Be understanding and patient, and continue to set and follow through on your usual limits. In part, it sounds like your son is employing the imaginary family to circumvent your usual routines or rules. At your end, just be consistent.