No papers.... how can I see if she is a pure or X staffy?

The puppy we are getting is through friends of friends.
They have both parents staying at home.
but these guys are not breeders, even though they love their dogs and you can tell by how clean and happy they are.

The dilemma I have (not really a dilemma but just some concern) is that they are KC registered and have no papers.
They ensured me both parents are pure staffy.
How can I be sure they really are? and therefore my little one is?
Do not get me wrong... it does not make any difference to me the pureness of the breed... I always got dogs from shelters... the concern derives by reading some posts where other members had issues with biting episodes or bad behavior related (in most cases) not only to lack of exercise and training.. but also to the parentage of the dogs.

I have a 3 year old daughter and are obviously aware that she will have to play carefully with the pup..... they are both so young and do not know what they do... but how can you impose a little girl to play on the floor with her puppy?
Anyway... my question is... Is there anyway that I can understand if parents are pure staffies and/or if my puppy is a cross?
Such as dimensions when is 8 weeks... or some somatic traits clearly belonging to Staffies only?

Let me know please..
It won't change our choice of course... but at least if we know her parents derive from some particular cross (say Jack Russel for instance) we know what to be careful with.

Thanks

http://staffy-bull-terrier.co.uk/standardataglance.html

http://staffy-bull-terrier.co.uk/kennelclubbreedstandard.html

Without papers I'm afraid it's guess work. I would also not let your 3 year old play on the floor with a puppy. If you are on the ground with them they think there is a different set of rules. It's okay to let them play but I would stay away from the floor.

No matter if your puppy is a cross breed or a pure staff u will still have to be carefull with pup around your 3 yr old. Pups have such sharp little teeth and untill u train it wont no its not suposed to use its mouth ie bite your little one. Its up 2 u as owners to teach pup whats right and wrong and until that stage has passed its probably not the best idea for your little one to play on floor with pup unless very strictly supervised

As above, without papers you will never know if its a x or not. Good luck

Many thanks...
I know about the floor thing... thanks to the forum :-)... so I will follow the rules.
I shall see some posts about teaching the pup not to nip from the beginning...

The hard part will be to agree with my wife a set of common rules to make sure our training is consistent and follows the same direction.....

Thanks again

Yes it is very important all members of the household follow the same rules please be consistent with the training.