
As we/I became more experienced at picking 'the most promising' in our litters, we only kept the rest to the normal, for us, 10 weeks before letting them go to their new homes. There's no doubt that people want their puppies from 8 weeks so hanging onto the entire litter for longer, could lead to problems - I can see people thinking 'what's wrong with these puppies'!! I'd plan on running on 2, or even the 3 we did once out of a litter of 9. Yes, people do have slightly older puppies available, once they've made their final choice, but with mine, so much can 'go wrong', or get better by 6 months in any case. And apart from one boy I had to home when he was 18+ months (fighting with uncle), those I ran on, I always ended up keeping!
As for sale contracts, what you put in them is entirely up to you - I just urge you to keep it brief and to the point.... if we try to cover everything that might crop up, given how people are these days (law cases!) a Contract could run into pages. And at the end of the day, unless drawn up by a solicitor (!), really are 'only worth the paper they are written on'. I had a specific one for a male I sold to a fellow breeder which included me taking one stud service from him. She sold the 2 I let her have abroad - so much for getting to him when I needed him. Too involved - and this was before Pet Passport so I ended up using his brother who I'd kept, but he wasn't what I wanted, for that bitch.
One of the musts for me, on a Sale Contract is that the puppy comes back to me, or I'm involved in any rehoming that might be necessary, at any age. Whether that could be upheld is anybody's guess. Many times an owner doesn't want to admit they've made a mistake so home without the breeder knowing.......