Programming one cell to respond to a different cell according to what has been entered.

[mumkiwi]

I'm convinced this can be done but I can't figure it out. I have 11 columns. 1 column is where I enter the name of a crew member that I want to schedule. The next to last column has a complete call out list of names and column 11 is 'scheduled?'
When I enter a name in the column 'person scheduled', I want the column 'scheduled?' to mark an 'X' beside the name matching that person. Column 'alphabetical call out list' can not be changed. It is an A-Z listing of all staff. Did I explain that right? Does anyone get what I need help with?
Thanks for taking the time to read this!
EG
COL 9 COL 10 COL 11
person scheduled alphabetical call out list scheduled?
tony aaron X
Joe craig X
sue jeff
Jenny harry
Craig sue X
aaron tony X th

[zbor]

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