modify page data

[Bertrand]

Hello

I'm sorry to post what is probably a basic question, but I couldn't find quickly an answer in the forum (I probably didn't search enough ?)
What are the best way and best practice to modify a single page data (or some of them) such as modifying <menu />, <parent /> etc ... ?
Thanks in advance - I've been coding my own page hierarchy editor but now I need to save the structure modifications and wonder if there is an easy way before digging into the existing code.
I'd rather ask before breaking everything

I reckon I didn't study the whole getSimple code before starting hacking together my plugins...

Bertrand