How to merge files

[Benjamí Villoslada <benjami@gmail.com>]

I can't see how to merge two files. There are two SPIP CMS translation files:

A) ca.php with catalan translation from a old version.
B) fr.php with the original and last version (french).

The goal is to put B new lines into A, but without removing the previously 
translated lines in A.

Diff & patch (with my limited knowledge of this tool) replaces translated 
lines in A because B have those same lines, but in original french. Perhaps 
diff & patch is not the right tool.  Any idea?

Thanks :)

Regards,

-- 
Benjamí
http://blog.bitassa.cat