Hard to tell how old your scovies are but they look full grown, but hey I have a 10 yr old and she is broody so just keep that in mind they may not lay till around 7-8 but they still love to brood. lol
My ducks have all been raised around our dogs so they all are around each other daily. But I will say mine cannot be around any thing peeping the prey drive kicks in big time so another thing to think about when you have ducklings since you have dogs. But if these haven't been around dogs it will take time for them to feel comfortable around them because being prey they have no idea who will want to eat them.
Put a roost inside the house on the water they may roost in there. Mine roost in winter but not in spring and summer they lay in their shaving so each night they pick their favorite place to nestle down for the night so they are ready to lay their egg in the morning.
Frost bite is something that will be a possibility mine have gotten it on the knobs on their faces I will slather Vaseline of something similar over their skin to help keep it from happening.
The more time you all are out with them they will get more use to their new place. I am sure if they came from terrible circumstances they are thinking they are in heaven at their new place. Give them time they will come around.
Does your pond freeze over in winter? you'll need a plan to keep them safe if they can't get in the water to get away from a predator. I think your scovies are too heavy to fly up into a tree. Especially laying females.