I have a 4 month old GSD mix who is about 25# and a 10 month GSD/Mal about 75#. I just got the GSD/Mal on Saturday and the two have been getting along great. However they play very rough, chase, tackle and wrestle with plenty of “play biting”. There is not a lot of growling, although the big guy will at times, I don’t hear anything from the pup. Every so often the pup yelps and then the other one seems to go after him more. The pup always comes back for more and doesn’t seem to be afraid, but I do worry about the size difference and one time the big guy grabbed the pup in the middle of his back, that made me nervous, usually they grab each other on the scruff or front legs. Should I let them continue or when it gets intense stop them? I do have a call into my trainer but I haven’t heard from her yet.