kitties playing & biting

Can you trust leaving a 7 months old alone with a 7 weeks old ?? They seem to be playing by biting..Yumosh never bit us hard, always lightly. Will she bite Mavish stronger while playing ? Are they supposed to play only by biting ?? When do you know that it's not playing (other than hissing & blood)..

My big lummox of a teenager kitty is 1 1/2 yrs old and she and Ripley play together continually. Rip was quite petite (1.6lbs) when he came inside to live as he was ill and a runt - and Noodles weighs in tipping the scale @ 18+ lbs. There is grabbing and nipping and wrestling all over the livingroom - fur flys!
So far, no problems - but I keep my eye on them to make sure there is not a problem. When Rip has had enough, he squirms away from Noodles - and being smaller and quicker, so far this has worked for him.

dodo,
You should be able to leave them alone. We started letting Scooter out of the bedroom when we were at work when he was about 9 weeks. In fact it wasn't that long ago. We watched them Gizmo and Scooter closely when he was younger. We really had to watch Gizmo, who is 7 months and a giant! They will play bite. The only time we knew it got out of control was when Scooter starting crying, so we took Gizmo away from him. I watched him especially when Gizmo wrapped his paws around his neck and kicked at him! Just keep an eye out and you will eventually know when it's ok for them to be together! Hope I've helped some! As long as there is no blood, then it's just play fighting.

Debra & Tigger, you helped a lot.. Thanks guys...