Expiry Date Indicator

Hi All,

For days I'm trying to create cells that indicates the start and the expiry date.

The Start Date and the End Date is located in Sheet1 while the formula reflects it on other Sheets.

Now the tricky part is: I need the indicated cells to be also available for data entries which stops me from entering any formula within cells.

Attached an end result sample in case my description is not clear.

Appreciate any ideas - Thank you