i have a nearly 3 years old female sib who`s a wonderul dog, dominant but well balanced with humain and dogs, she is playfull and loving, and i introduced a 8 weeks old puppy in the winter, from the same breeder same parents as her, and the introduction was not without trouble, my female became very possessive and territorial, she was rough with the little one and we had to let them go outside separately and i had to watch all the time when they were playing together, even so when they go to doggy day care my female who never stop playing with other dog, doesnt play anymore, she mother him, she watch if other dog are rough with him she never enters in conflict with other dog her body language is strong enough that they leave the puppy alone and the puppy is a great dog, let the female dominate him but he is getting a little stronger so she is playing more now with him than before, but now my female started peeing in the house..... its sometimes hard to introduce a second dog even if you do everything to make it right.... any advice guys??