Alpha Dog problem

Question
About a month ago, my family bought a standard poodle, she is almost 5 months old now and she is not going to be spayed. Her name is Ellie.
So when we got her, we already had another poodle. Her name is Gracie. Gracie is a 2 year old miniature poodle, although her size is closer to a toy poodle.
When we brought Ellie to our home, Gracie reacted excellently to the new dog. She shared her toys and played with her and everything.
We noticed though, that sometimes the playing got out of hand because Ellie was bigger and rougher with the little dog.
We don't think that Ellie is trying to hurt Gracie, or try to make her submit, but Ellie is definitely not backing down to Gracie when Gracie bares her teeth or growls.
So Ellie thinks Gracie is playing when in truth, Gracie is telling her to back off.
We want Gracie to continue to be the Alpha dog, but with Ellie growing rapidly and more rough every week (of course not trying to be mean, just playful) we are wondering what we should do!!!
We love both of them so much and don't want any harm to come to either of them when things do get out of hand... please help!!!!
We've taught Ellie not to bite when we say "no bite" but she gets wild when she plays with Gracie and we don't know what to do.
Gracie remains unharmed and without injury, but we fear that that might not last!!!  

Answer
Better leadership on your part may help.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm