Tricking the file system to mount a LINK2SD drive as mnt/extsd
/mnt/extsd/179_49 
/mnt/extsd/179_50
/mnt/extsd 


some type of round-robin.

Your going to have to move your data in '49 &amp; '50 to someother directories. mkdir /sdcard/externalData

rmdir '49
rmdir '50
rmdir extsd

cd mnt
ln -s /sdcard/externalData extsd

cd extsd
ln -s /sdcard/new49 179_49 

ln -s /sdcard/new50 179_50


Whether this will work will depends on the capabilities of ln.  This would work in normal unix  / linux boxes.  

R