P.P.
I pretty much agree with what the other moms have said - but keep your expectations realistic for her age - and keep them expressed in very simple words. Long explanations won't compute at her age. It will be much more satisfactory for both of you if you don't expect emotional maturity that she is not capable of. Short simple instructions for her like "we all sit in our chairs when we color" - and then let her sit by you. Would there be problem with her sitting on your lap while you sing songs and read during class time?
The other girls know you are her mother - and I don't believe will feel neglected if you share your affection with her and also with them in an appropriate manner. "Come on, girls, let's cozy up for story time." It's not like you have a class of 10. And these are really very small children - and won't stay this way for long. Enjoy them as they are.
Good luck - from a grandma who has to be shared, too.
Good luck.