So currently I have 3 comet goldfish in my aquarium, but I want to put them in my pond which contains of around 15-20 koi fishes. I would prefer them to be in a pond so they can swim around in a bigger area and don't get stunted.

Two of the comets are about 2 inch while the other one is about 3 inch long.
The koi fishes that are currently in the pond range from around 4-15 inches. Most of them are over 8 inches and some are new little ones around 4-8 inch.

The pond is around 4 feet deep with 5 feet in width and 6 feet in length. My dad got the pond made with the builders so it does not have a certain size but using the dimensions the pond could be 600-800 uk gallons.

So I'm wondering if the little goldfish will survive in the pond. The koi fishes are very friendly but would they chase the comets around and get them stressed?
The comets mouth aren't big enough to eat a koi pellet so can they eat of the algae until they are big enough to eat them or can I put goldfish flakes in but I doubt they'll get to eat them as koi might eat them. Also the koi fishes only eat once a day and never during Winter. So will the comets eat during winter and do I have to feed them once a day or twice?

Thanks for any help :)