Same thing here! First time letting the momma hatch the eggs. First baby hatched today, one other egg has piped and three others are left. At first, we had no idea she was hoarding the eggs, and figured we would leave well enough alone. One day we got curious and lifted her out, and she had a clutch of over 10 eggs. Way too many for her size. So, we marked six and left them in. She threw out two just last week and kept the remaining 4. However, she kept trying to add to the group. Since we had marked them, we knew which ones to remove. We knew the day was getting close, but because we didn't keep record, didn't know when to expect the hatching to begin.
We are going to probably have the same issue with her leaving the nest. She is still sitting, and we expect she might continue to for 2 more days. Next time when we notice a broody hen we will be sure to mark the eggs right away, and collect any extras.
I think the only way to save the remaining eggs is to use an incubator. Good luck.