Input to one sheet from another

I have two sheets in separate workbooks. #1 sheet is "QTY By Inv Customer" #2 sheet is "XX.2017 Airport Fuel Billing"

Sheet 1 layout is:

account | jan | feb | mar | apr | may | jun | jul ...
user 1
user 2
user 3
user 4
etc

Sheet 2 layout is:
account | account # | 100LL | 91UL | JetA
user 1
user 2
user 3
user 4
etc

On sheet 2 the last three columns may or may not all be filled in. What I would like to do is to look at each user and see if there is an entry in any of the three columns, if there is then I would like a X to be placed in the appropriate month. (sheet 2 is different sheet for each month). I thought that I could do it using conditional formatting, but I cannot for the life of me figure out how to phrase the equation.

Thank you for your help.

Joseph Carney, C.M.