Updating a TTree entry

Dear ROOTers,

    I would like to know if it exists a way to update a TTree entry. What I would like to this is more or less the following:

1. Opening a TTree and properly set the branch address to a local object
2. Get the one entry
3. Modify the local object containing the branch content
4. Updating the branch replacing the current entry with the content of the modified local object
5. Saving the modified TTree on disk.

I tried with TBranch::Fill but this is adding another event and this is not exactly what I want.

Can you help me?

ROOT 5.15/08
Linux
gcc (GCC) 4.1.2

Thanks,

Antonio

-- 
Antonio Bulgheroni, PhD

Computers have a lot in common with air conditioners:
Once you open WINDOWS, they stop working properly.