Thank you everyone, to answer some of the points raised.
The dogs are not really ‘together’ all that much really.
They wake up around 6, have breakfast and are together until around 7 when the puppy usually has a nap ready to leave at 8.10 for a walk.
We get back an hour or so later and both dogs go toilet and settle down to sleep, usually until about 12/12.30 then when they wake up they are fed again.
They are together again until about 2 when they both go to sleep again ready for another walk at 3, back at 4.
Together for about an hour or so until I feed them dinner, usually awake another hour or so, 6.30/7 they tend to sleep again, brief wake up around 9/9.30 then to bed at 10 where the puppy goes into his crate.
So all in all, they are only properly together about 4 - 5 hours split into small hour or so segments.
They sleep cuddled up together sometimes and my older girl doesn’t seem to mind at all.
I can’t separate via gates as the puppy is so tiny he can actually fit through the bars!!!
I do have a downstairs crate and I do put the puppy in it for short periods if he’s harrassing her.
The dogs are trained together, he is already getting good at sitting and waiting politely outside the school, shops etc.
He can do some tricks but tbh, he isn’t at all biddable and handler focused like my girl is.
He’ll only perform tricks if he’s hungry and while my girl loves to play with people, the puppy likes to play with toys independently, he will not bring toys back, he just likes to bounce around by himself shaking the toys or play tug but even then, after a while he wants the toy to himself.
Frankly, the puppy isn’t affectionate at all really, he wants to come up and sleep on your lap for naps and he runs and greets people joyfully but he isn’t into stroking and cuddles like my girl is.