Copy row data to multiple other cells

What's the best way to allow users to easily copy data from one cell and apply it to other cells, without using key combinations?

I was thinking about dragging cell borders horizontally or vertically to apply data to adjacent cells, but the cell is also a drop-down, so I don't know how to activate those borders without expanding the drop-down.

Context: this is a form to request new hires with different schedules.