Multi string text return in same cell

Hi,
Need help composing a schedule
I have a classroom of 25 kids
During certain hours some of the kids will attend other training
What's the best formula to use?
Header should be M-F

Vertical column will be 9-4

I will manually enter the names of the children into a single cell who will be absent during that time period

In the final column I need the names of the remaining children in a single cell


What are the best formulas to use?

Thanks