The info in /home/var will be "linked" to /var ,isn't it? All new files will be stored in this /var?
Yes the files in /home/var will be linked to /var. So the files will not actually move from /var and new files will be stored in /var.
If you cannot change your configuration file to point to /home/var I would suggest you move what you want to move from /var to /home/var and remove that directory and then create symlink.
/var/test is 500 MB.
cp -rp /var/test/* /home/var/test
mv /var/test /var/test-orig
ln -s /home/var/test /var/test
then all new files will be stored in /home/var/test but you do not have to change your config file because /var/test still exists but it is symlinked to /home/var/test.
Test your application to see if it works. If it works then you can remove the /var/test directory.
rm -rf /var/test
Becareful of your commands when doing this.