I have not candled the eggs yet. Day 10 is Sunday the 4th. I usually wait til then to candle. Unless I have a lot then I candle a few each day.
One broody is Frenchy and I'm worried since she is old to stress her out by making her sit for a longer time. The other is a Marans and I think she can handle 6-8 eggs. IF she stays sitting once I move her. I have to since other hens are adding to her load.
I would candle right before you get these before you make a decision that maybe you didn't have to. I don't know what kinds of eggs these are you have in the incu and under the broodies but I just candled my Silkie eggs on day 4 and my Orp eggs today and could tell very easily that they were developing. Reason being because if they were clear I would have removed them and/or added more from the other Silkie. She's small so I didn't want to add too many. It's amazing this little thing is sitting on 7 Silkie eggs and 3 Orp eggs!

On my way to Metella's the other day I almost took out someone's pet duck. It was just standing in the road and couldn't be bothered to move when the car came up on it. I had to go around it slowly. I told it it was lucky I owned ducks or someone not quite as fond of them may have wiped it out.