Advice on 21 week old and 10 week old puppies

[rubyrules]

Hi, so I hoped to benefit from others experience if I could. Lottie, 21 week old cockapoo met Nellie, 10 week.old cocker (very tiny) for the 1st time. We were very calm and nellie was really timid and submissive, Lottie did fantastic lots of licking and laying next to nellie, we made sure that we made a fuss of them equally.
Fast forward to next day, very good at first then nellie had been asleep so was full of energy when she woke up. Needless to say she wanted to play so Lottie thought she had the green light to be her mad puppy self. Made worse as she had come in from a toilet trip outside in the rain and was wet through, which sends her crazy!!She took great pleasure in biting nellies legs, chasing her etc. Nellie was still wagging but running and hiding when it got too much and doing a bit of crying out, but then going back for more.
I do not think lottie would be anything other than playful but due to the HUGE size difference and the fact that lottie herself has no idea of her own strength etc, we were scared that she would hurt her.
Any ideas on how we should manage this? If lottie was an older dog, I would feel more confident that she would let nellie know how to behave and put her in her place. But lottie is still a pup herself so doesn't have boundaries.
I will be looking after nellie on a regular basis, so they will be seeing lots and lots of each other.

[Bettylove]

I would be looking for mirroring behaviour and turn taking , if it starts to get more one sided then intervene and separate them. I would always separate them if possible before they are ready. Puppies are robust though and do play rough and tumble and quite often there is squealing. My cocker pup plays with Labradors and a husky mix and my pup is the worst for leg biting and the older ones let him get away with it so I intervene when he gets too bitey and his barking gets too excited and frantic. I look after my daughter labs weekly and one is a seven month lab and I have a five month old cocker. Separate cages I have found to be a must (in the same room- they can still see each other)and opportunity for lots of sleep as they can get worse when they are over tired. My pup has more crate time when the labs are over than a normal day but he needs it as he plays more and I find I have to regulate him more. I also take them out each on an individual walk. It does get better but it was very intense and exhausting for the first couple of months. Now they are starting to take themselves for time out .