There's a lot more information I think I would need to know from the family but being the child is adopted it would be almost impossible to get any sort of family history makers of mental health disorders or other information that I would need unless it was an open adoption. I would however check with the adoptive parents to see if obtaining this information would even be possible. I would also ask them if Sarah has had any recent trauma to her life to cause these fits, or if her acting out could be a result of the recent adoption. Maybe why she was adopted her why her bio family gave up on her.
After the basic interview I would ask to speak to Sara alone just to see if she would open up. Being a parent myself I understand that sometimes children have a fear of speaking in front of their parents just for the simple fact of saying something wrong and getting in trouble. A lot of times they would rather speak to a stranger to speak to somebody who cares about them.
I do feel that yes, more information is needed in this case for any type of actual evaluation to be completed. This family in particular there are some factors for effective intervention that would be things like child's play therapy or a group setting with other children maybe to get her more socialized. But as for any type of diagnosis it would be very hard to do at this point with such little information.
When entering her information into the five axis system you would maybe put the fact that she has stopped wanting to attend preschool in axis 4, under educational problems. You could also put her sleeping and eating problems under axis 1, but you would also have to take into consideration that this child is only four years old. I personally have six children, four of which have already turned four, and I think each of them went through a phase when they acted out for no reason at all so with this child maybe that is just it she's going through a phase and...