First, it is best that the first one is pretty well potty trained! We have one that is 6 yrs. one that is 9 months and one is 4 months. We brought Tatiana home when Teeka was 8 months. Teeka is potty trained for the most part. These 2 have got along great from day one! Teeka really needed a playmate and I wanted them to grow up together. It is funny, now that Max would never play with Teeka before we brought Tatiana home. Now Max has decided to join there games of chase! He gets just as excited as they do, especially in the evenings.