Merging 2 itunes libraries

is there a way to merge 2 itunes libraries?

on my old G5 stuck at 10.5.8 and itunes 10.6.3 (name it library A) I have over 8000 songs. And on newer Mac Pro tower, with OSX 10.6.8 and itunes 11.1.11 (name it library B) I have an itunes library that has approx 150 songs, but all of my kids ipods, and iphone have already been synched to this itunes library B, for compatibility and latest software.

if I try to sync music with Lib A, it ask me if I want to erase the ipod before proceeding, cuz the ipods have been previously synched with Lib B... so I do not want to erase, as there are games, photos, data, contacts etc.. that will all be erased as well.

Is there a way to merge Lib A to Lib B, using the .XML file in the itunes folder? How about the .itl file? and the com.apple.itunes.plist one??

and symply manually copying all of the 867 folders containing all the music into Music->itunes->itunesMusic??

Will the itunes 11.1.11 recognize a .xml file done with itunes 10.6.3??

Thank you for the help

Michel