Copy/Paste Overriding Data Validation

I currently have a spreadsheet with a lot of data validation settings in the cells. About half have some kind of drop down list while the others have another form of data validation (i.e. takes only decimal numbers, takes only dates, limits # of characters, etc.).

The problem that I am having is that people are copy and pasting data from other spreadsheets into these cells. This overrides the data validation settings with the format/settings of the cells the data was copied from. I allow users to paste into these cells as long as the pasted data meets the data validation requirements or matches one of the possible drop down selections. For example, if the drop down options are "A", "B", and "C", I want to be able to paste "B" but not "X".

I have done some research and have noticed that there are some macros that have been made that allow users to only copy and paste values. This maintains the data validation settings in the cell; however, users are still able to paste values that do not meet the data validation requirements.

Does anyone have any ideas?

Thank you for the help. I really appreciate it.

How does this macro work. Does it prevent copy/paste? I'm okay with users dragging down their selections in each column and with them pasting selections that meet the data validation requirements.