We are the happy owners of a 12 week old lab and a brand new westie pup 9 weeks, the lab has been with us for 2 weeks the westie 2 days. We have had dogs for many years and previously had the same breeds who both passed away at ripe old ages we are concerned about aggressive play and obviously don't want either dog hurt and realise it's part of growing up, but would appreciate any advice or tips on calming it down slightly. Needless to say as I,m posting this they are snoring side by side.

Two puppies of very similar ages will play hard; it'd be a good idea to separate them a lot of the time to make sure they bond with you more than each other (google 'littermate syndrome' - they don't have to be littermates to suffer from it). This way they'll be more responsive to you and therefore more easily controlled, including the level of their play.

An easier solution would be to raise one puppy before introducing another. It is generally much harder bringing up two puppies at the same time, in your situation this might be compounded by the fact that one puppy is large breed and is playful and doesn't quite realise its strength, while the other puppy is small breed and a terrier who might well decide he doesn't like the goofiness of the large breed pup...

So basically patience and perseverance will win out, luckily I, m not working so l have entry of time to work with them and its summer that helps. We have done this before with 2 pups but you do forget over time. Thanks.

And spending time Individually training  each dog so they build a bond with u and n ot just each other
.given their different sizes and probably play styles i would carefully supervise play and give them time separated as well.

I would never recommend taking on two puppies at once.  (I'm a trainer and behaviourist.)

Terrier play can very easily tip over into reactivity if/when play becomes heated and over-excited.  Labradors are notorious for playing 'hard' and rough, and are very very likely to tip terriers over into reactivity.  It's not a combination I'd even have off-leash together during puppy play at class, let alone a combination I would want to see living together. 

You might want to see some of these links:

https://youtu.be/LSEno_YxhMk 

https://youtu.be/jfZ5n-N1sJk

http://www.whole-dog-journal.com/issues/13_1/features/Problems-Adopting-Two-Puppies-At-Once_16190-1.html

http://blog.betternaturedogtraining.com/2013/07/18/littermate-syndrome/ 

Frankly, whichever is the 9 week old, I would return that puppy to the breeder for a full refund and enjoy the other pup.

We are now into July and the aggressive play has kinda died off, though they still have there moments we are taking them to puppy training and have had some very easy and constructive tips to try which are really good, at least one walk separately a day, good idea, take them to busy places which we knew, play firework videos on YouTube. To many to list. On the 2 puppy at once opinions I wouldn't disagree with the it's loads more work but you know what happens when you get 2 people together? A difference of opinion, thanks for the replies.

We almost always kept two, and once three (great litter that one - 9 puppies and we kept 2 bitches and one male) puppies from our litters without problems.  I suppose it's a hound-thing but very rarely did we have serious fights (although once we had a nephew/uncle situation when nephew was around 2 years which resulted in him eventually having to be homed, for the sake of peace in the 'pack').   I would say that sometimes when I look back, I wonder how I coped with puppies and X-number of adults    Clearly I was younger and fitter!

Our second hound, buy-in early days, came when the first was almost a year old however and I think this is how novice owners should be encouraged to start given that one Basset is NEVER enough

They have never caused injury it just seemed super rough and a bit scary but it's calming down. Puppy classes will hopefully help, there training there humans well