I have a 11 week old SBT bitch and a 15 mnth old SBT dog, I let them play together most nights so they can get use to each other.  Thing is she never leaves him alone nipping his face all the time, he just plays with her very gently.  She goes mad never rests and plays solidly for 2 hours with no break! Eventually he just wants to sit down on his own but she wont leave him alone, I do want them to be together in the future, keeping them separated at mo, with her being so small.  How long will this go on for? shall I watch them and just let them tire each other out? is 2 hours aday together enough? keep them separated with a baby gate, so they can still smell and see each other.
Please advise, thanks

Having brought an SBT pup into our family with our older SBT I understand entirely what you mean :)
You do need to seperate them and supervise- the older dog could unintentionally hurt pup too.
They will be fine in the future if pup is taught what is acceptable and what isnt acceptable behaviour :)

its a great idea to keep them apart but i would let them be together for more then 2 hours aday. maybe a few hours in the morning and as son as you notice that your older dog has had enough then keep them apart for a few hours and then do the same in the afternoon, the more she see him the more she will learn that its not all play