Hi Dab,
No expert here but I would suggest to have a separte tank for the goldies for a week or 2, the reason being is the water that they come from may not be as prestine as the current water that you have that can risk fish health.
Ick, fish lice are some of the few, protozoans may also be present on the fish itself. the 2 week period should allow you to see how the fish eats, moves,behaves. I am basing this on my experience with keeping tropical/aquarium fish which goldies qualify to be.
I have lost so many goldfish since I was in Highschool to Ich, fin rot and lice that came fish from different sellers.
You can try observing if the bluegill goes agro on the goldies by adding a few first, goldfish are pretty nosy so if bluegills are territorial that will cause troubles.
I have a 2 Rosy Barb's mixed with some goldies on an aquarium system and the Barbs annoys the goldies attempting to nibble on their Fins, my goldies are bigger than the barbs and they just shake them off easy.
These are all based on my experience its been right since until date unless corrected
.Kindly consider first point mentioned.
MARK