[Biopython] editing xml blast report

[Yvan]

Hello All,

I am wondering if it is possible with biopython to correctly edit a xml 
blast report?

Here my problem;
I need to filter/exclude some hits according to their length but the xml 
consistency should be conserved.

Should I parse with it with NCBIXML and recreate a xml file with hard 
coded tags? I try to use the tabular output of blast+ and reformat it 
with blast_formatter but with no success.

Any one has an idea or some pointer I could use?
Thanks a lot for your help
cheers
yvan