I have just introduced 11 week old Stanley to my 2 (male GSD 7 yrs & female x terrier 6 yrs old) Zak has been brilliant, only growled once & that was when Stanley jumped off the settee onto Zak's back (he was asleep at the time!). It's Tilly who is the problem, she acts like Mother Superior, she won't play & Stanley is absolutely desperate for her to play with him. She has really given him 'what for' on a number of occasions, but he just shrugs it off & comes back for more. She hasn't marked him or gotten hold of him, it's a lot of noise though & snapping. She seems to detest him racing about. The odd thing is though she is normally so playful with Zak, all that has stopped since Stanley arrived. I obviously don't leave them unsupervised & am intervening with a loud 'Ah'. It does stop them both in their tracks. Should I let them get on with it, or intervene, as I am doing at the moment?

This is a hard one, personally I would intervene as you are doing but some say let them find their own level. I wouldn't do the latter as it would/could get too heated and somethin nasty may happen?? Just my view
The 'Lady' of the pack is just probably saying to the young 'oyk'..I was here before you & am much older... so mind your step!!!

i had the same problem with my last addition to the family and one of my other dogs. i found ihad to take things very slowly and not ver let the pup jump on or annoy my older bitch. i also used star gates so they had time apart and always left an escape route for my girl to get away if she wanted to.
making them put up with each other will not help, some dogs just don't like the bounciness of puppies and take a lot longer to get used to them also the puppy needs to learn some manners and self control.knowing when your other dog wants to play or be left alone.
i found putting either the pup or both pup and other dog on a lead while we sat in the lounge was good, as they could see but not touch.
Also letting them out in the garden at different times for a while so your older dog doesn't get chased or jumped on.
taking them for walks together helped with bonding but make sure they have space in between them, easier if you've got someone to help walk the dogs.
my dogs took a good few weeks to accept each other and i'm sure for a few months my bitch was hoping the new pup would go away but we got there in the end.
just take things at the dogs pace and things will slowly get better but never leave them a lone together until your really sure everything is ok. i still sleep mine in separate places or with a stair gate up just because there's no escape route otherwise for my older dog but really their pretty good friends now, more me being over careful.    
your dog  may well be a bit frightened of the pup and this can come out in aggression so just let her come to terms with your pup and i'm sure in a few weeks their be friends.