This is a bit of a strange question:

My brother and I both live at home and we each have SBT bitches.  Both had a litter at the same time (mine was planned, his was a mismatch with the amorous next door SBT - she escaped past my small niece and jumped the ajoining fence.  Told him to get the mismatch injection but he decided to let her have the litter.  Big arguments.  Don't ask.)  He has now decided to keep a dog from the litter.  Our two bitches get along very well, his bitch seems to think that my bitch is her puppy.  By the looks of it the dogs are going to be big, as both his bitch and the next door neighbour's dog are considerably larger than my bitch.

How can we best work things to ensure that it goes as harmoniously as possible?  Obviously I don't want the dynamic between our 2 bitches to suffer because he's decided to keep a dog.  Also I worry that his bitch may decide to attack Benny (my bitch) if she plays too roughly with her puppy.  I'd really appreciate some advice on this matter as I'm quite worried.

You can keep mother and daughter staffies together as 99% of the time and it will be a harmonious realtionship and you will find that a dog will usually fit into the structure no matter who he is bred from. As long as you keep an eye on the dog and bitches around seasons you should have no problems. The problems arise when you have an Alpha bitch, in this case your bitch, and you try to bring in a bitch from the outside to live in the same house.

Thanks, that's really set my mind at rest!  My bitch will definitely be getting spayed as soon as is safe as she was miserable throughout her pregnancy.  I think my brother's planning on spaying his (the accidental pregnancy more than convinced him that it's a bad idea) so hopefully they'll all get along just fine.