I have two girls as well, 1 yr and 3yr. With the age difference, I have had some pretty rough play around here.
I just have to call their names and they stop and look at me with tails wagging so I know they are playing. If I see that one is getting too rough I put a stop to it immediately.
With puppies, I think you are going to have a ton of play but you are right to not let it get out of hand. Their mom would control this type of thing.
***I also noticed after I had my girls both spayed, the spend more time actually playing with eachother and toys together than fussing/"fighting".