Although there is not a function that allows breaks and lunches to be planned into the Build Schedule directly, there is a work around.
When scheduling a build at a time that will include an employee break, drag the build to the starting time, as usual.
Now, edit the quantity to the amount to be completed before the break.
That amount will be scheduled and the remaining quantity will return to the side bar.
The remaining quantity can be scheduled at a later time that day, when the break has concluded.