microsoft excel - How to color fill cells between range of dates

I'm trying to develop an Excel spreadsheet to manage staff holidays. The idea is that there is a "Calendar" spreadsheet showing which holidays everyone takes. Here is the screenshot:

I use conditional formatting to fill the cells. Row 3 is formatted as date, showing only the day. I compare the first holiday day (column B) and the last (column C) with the corresponding cell of the employee row. If it falls within that date range, I fill it with green.

The problem with my current setup is that the holiday periods taken by the same employee are shown in different rows (see rows 4 and 6). I would like to show all the holidays on the same row for a given employee.

How can I achieve this? I guess I need some VBA, but I don't know where to start.