Hope someone can help with this!!

Here's roughly what I need to do - as an example, I have, essentially, 7
tables of daily information that begins as exactly the same data for each day
- i.e. each day's information is a copy of what is inputted for Monday, so
for the remainder of the week, I will be using, for example "=Monday!A1" for
each other day.

Now, what I need to be able to do is on Wednesday, for example, change
perhaps a few words of the information (at the moment, a copy of what is on
monday), but for this new change to be carried forward for the remainder of
the week.

This is a simplified version of what i need to do, but what I suppose I'm
asking is how I can progressively change information that only starts off as
a copy of text in an initial table of information.