A couple of ideas for you.
As you can see, your ducklings are growing at a phenomenally faster rate than the chicken chicks. You may want to consider moving the ducklings out. In fact, ducklings can graduate to no heat and acclimate to outdoor temperatures at a younger age than chickens can.
Second, at two and four weeks old, I would be combining the bantam chicks with the large fowl chicks immediately. That way they blend and establish pecking order at a younger age, which is easier than waiting until you have a huge size difference between them and trying to make older birds integrate with one another. But, with those big clodhopper ducklings in there, the bantams might get trampled. So another reason to separate the ducklings.
And finally a third reason to separate the ducklings: you only have 3 of them, presumably one male and two females. Two females might be enough to keep the drake satisfied when he reaches sexual maturity, but if he has been raised with chickens, he will not think twice about trying to mate with them. And that can have fatal consequences for the hens because their anatomy cannot accommodate a male duck’s penis. Usually the suggested way to avoid that and still free range ducks with chickens together is to make sure the drake has enough female ducks to keep him happy, and then he will leave the chickens alone. Two might be enough, but raising him separately from the chickens and then reintroducing later also helps. Because then he doesn’t grow up thinking chickens and ducks are the same.
(So now that suggests that having a second coop would be good for separating the ducklings now, and then potentially the bantams later after the ducks get put back with the chickens. In the end you may not need a second coop, but I can tell you it is great to have a small empty space for the odd situations that are likely to crop up.)
Good luck, it sounds like you are having a lot of fun with them!