How to update linked data from a closed source

Hi,

I am trying to carry forward totals for a list of project numbers from Jan to Feb, Feb to March etc. I've got formulas in place to do this but I want the links to update automatically when I open the workbook without me having to open every previous months workbook. I'm sure there's a macro I can use to open, update and save and close the other workbooks but I have no idea how.

Otherwise, is there an easier way of doing this that I'm missing? I don't want to auto open 18 months worth of spreadsheets in a years time!!

Thank for any responses

Thanks Nathansav, I have something similar set up but as an array formula, I.e 'if a1=x then populate with value for x from workbook 2' but this only works if 'workbook 2' is open. Also because the data in workbook 2 is being drawn from workbook 3. (And so on from May back to January) I have to open all workbooks for the figures to update. Trying to find a way round doing that