Nice. I bet they love the extra space.
Can you keep goldfish & minnows together? I'd kinda have thought the goldfish would try to eat them.
Goldfish generally get along fine with minnows, minnows grow to a couple of centimetres long and are very good swimmers as well as living in shoals. Goldfish usually don't even try to eat them and have a vanishingly small chance of pulling it off if they try. Since my goldies are fancy ones they're rather slow and clumsy. Two tails and egg shaped bodies isn't great for swimming after tiny things. I'd be hesitant about a full grown normal goldfish, but not overly concerned.*
The danios I've got are about minnow sized at the moment and the goldfish haven't even acknowledged them for example. Nor have they bothered the hillstream loaches I've got even though they're very small at the moment. Mostly they just murder plants, root around in the gravel, beg for food whenever humans go near the tank and the big ones sometimes bully the smaller ones. I used to help out at the pet shop I get my fish from and minnows are usually kept in with the goldfish there. The odd danio sometimes winds up transferred across somehow as well, though they have a separate tank a good four feet away from the goldfish tanks. One lived with the biggest goldfish there, about 8-10 inches, for months before I decided to move him across to the other danios so he could shoal properly.
All that said goldfish aren't good community fish, they're big, poop a lot and don't shoal with the little guys at all, but I think a more varied array of fish and plants is probably more stimulating for them than just goldfish and should help cut down on the big ones picking on the little ones.
* A lot of small aquarium fish are actually more of a threat to goldfish than goldfish are to them really. A lot of cichlids would outright murder them, barbs would probably shred their tails, guppies/platys would probably snatch a nibble when they could, some plecos and other suckers eat the slime coat off them which causes oh so many problems. Fortunately most are outside the overlapping temperature range for tropical and coldwater so people don't try to keep them together, but suckers usually overlap and cause problems.