HI Hoping for some help on some formulas / coding

One workbook but about 25 worksheets

The first worksheet is the Mater Worksheets, with 4 critical columns

A B C D
Txt Txt Numeric Date

This worksheet has about 800 lines

What I want to be able to do on subsequent worksheets is

1) Manually enter a value in Column A, have this value checked against Column A on the Master Worksheet, and then have Columns B, C & D auto-populate with the corresponding values from the Master Worksheet

2) And, if the value in column C & D on the Master Worksheet change, for this to be reflected on the subsequent worksheets.

If this combination of is not possible there may be a simpler solution, given that the user has already manually populated all these work sheets!!

The alternative is a formula for the subsequent worksheets. On these worksheets check the values of Column A & B, find the corresponding entries in Column A & B on the Master Worksheet and then enter the values of Columns C & D from the Master Worksheet into the subsequent worksheets, Coulmns C & D.

I'm sure I've made this over wordy but hopefully you get my drift.

Many thanks in advance.

Dermot