Substituting values in cells having data validation

[scorpiansaru]

Hi Experts,

I'm new here.....

Here is my problem:
I'm using a list as data validation in some cells. I want to have one value in one cell only and that the values should not be repeated. So for example, if the list has three names: Dave, John, Patrick, the user should be able to select each of them in a single cell only. Additionally if they select a name other than the one selected, it should replace the names.
e.g.
Cell1: Dave
Cell2: John
Cell3: Patrick

If user selects Patrick in Cell1, the contents should be:
Cell1: Patrick
Cell2: John
Cell3: Dave

Is this possible??

Thanks in advance!!

Regards

 

[scorpiansaru]

Guys any help