[O] How to send a patch of a patch...

[abonnements]

Hello,
     yesterday I made some change in doc/org.texi and (thanks to 
Bastien) I sent the diff patch (obtained by C-x v =) that I send here.

    Today, I made some other changes on the same file, but C-x v = give 
me only the diff between my version of yesterday and the one of today.

    As I think (may be wrongly) that a patch must always be given 
between the original file and the latest newer version what is the right 
method to do so?
Thanks.
Thierry

PS: I managed to get what I want in recloning org-mode.git but it seems 
not to be the right way.