hi @OddSocksSparklyDocsandDungaree - does he have a good retrieval instinct? does he give up balls, toys etc when asked? My current retriever will happily retrieve ANYTHING just for the joy of doing it - I can send her for toys (belonging to the other dog), balls, gloves. She loves things being hidden and then being sent to find them. Not all of my retrievers have been this interested, some would prefer to just deconstruct toys (my DC had a lot of armless, legless, dolls growing up - when they left anything near the reach of one particularly obsessive doll murderer).
If he does bring things back then playing hide and seek with toys is a good game, you start by showing the dog and child that you have the toy, then you make a big deal about hiding it, say under a box or behind the sofa - and then you ask the dog to find it. Repeat.
If he won't retrieve but he will catch, then you play the teaching them both to count game. A very slow and clear '1,2,3,4...... FIVE!" - and on five you drop the toy into his mouth. You don't throw it, you calmly drop it - and you stop counting if the dog moves from a sit - you don't want him standing, but sitting. The toy is the reward for the sit and waiting until you get to "five" The dog begins to anticipate the "five". It's a good indoor exercise to teach a dog anyway because there might be times when he's confined due to injury and you want some way to keep him amused without having to rocket around the place.
If you do it after he's kindly cleaned up for you when she's in her high chair then she's safe off the ground and can "help" you drop the toy.
You really do have to put in the work with the dog and train the behaviours you want, then try to teach your DD how to get those behaviours. If anything you are doing is making either of them hyper then stop - you are trying to get calm and focus from both of them, don't overdo it - better to have 2 or 3 successful little interactions and stop.
young dogs and young children are both hard work, but I never regretted having them together, loved watching their interactions.