The feature you request already does exist in BearShare...

In the DownLoads Page you may select one or more files in 'the usual manner' and then

Right-Click and you will see another small menu appear...

Select Find More Sources.

__________________
Fusion for REAL!--CDex 1.51--Wackyuses--Bitzi - Check Files Before Download !--.mp3 File Name Change Problems? Try Rename-It!--Alternate PORTS--Avast- Anti-Virus--WindowWasher--IrfanView--PC Pitstop - Test your PC !--Mac OSX Troubleshooting--GO .ape ! - For 'Lossless' Audio Compression--Port :6346 - Test If It Is 'Blocked'--Cole2k Codecs--OldVersion - Newer isn't always better !
Nod32 - Free Virus Scan: Use ESET's Online Antivirus Scanner

Tomorrow's forecast:
Sunni in places, Shi'ite in others...