Excel formula/function help! Please

Hello!

I have:

1. 2 worksheets in same work book (worksheet Bill & worksheet Casey)
2. each worksheet has Col A - client #s and Col D - status

Here's what I need to do.... I hope someone can help. Need to write a formula/function for the following:

When Casey updates her Col D (status) - I need Bill's Col D to update with that information

BUT: the rows may be different in each worksheet - sooo... when Casey changes her Col D, Row 1- I need Bill's Col D to check for a match in Col A (client#) ANY ROW.

So if we have client# 999999 in Col A, Row 1 on Casey's worksheet and she changes status for that client in her Col D to "On Hold"

Bill's Col D needs to check Casey's Col A, Row 1 client# to match to a client# in any row in Bill's Col A and if it does - populate Bill's Col D with the text from Casey's Col D, Row 1.  ("On Hold")