Valid If help (Contains formula excluding current rows)

[Mic_L_Angelo]

Hey folks, could use some help here.

Got a table called “Managers”, listing managers in my group.

Manager Table has a “Coverage” drop down column.

The drop down selections are
Places,
People,
Travels,
Travels, People
Places, Travels
Places, People
Places, Travels, People

I need a Valid If formula that states "A manager cannot select an “Coverage” entry if another manager has already selected a “Coverage” entry that contains the first.

In other words, Manager 2 cannot select “Places” if Manager 1 already selected “Places and People”

The best I came up with is below

NOT(IN([Coverage], SELECT(Managers[Coverage],
[MANAGERS KEY ID] <> [_THISROW].[MANAGERS KEY ID])))

This only prevents the exact entry from being re-selected
(Manger 2 can’t select “Places and People” if Manager 1 already selected “Places and People”)

I basically need to add a CONTAINS formula for this to work as I need it to.

Anyone willing to be a jolly old chap and help me out?