Both grub & fstab have entries to partitions, but device, label, or UUID. So you also need to update grub. But if booting from one install it should let you directly boot into the other installs.
Post this to see entire configuration. This is a new test version of the boot script to try. It will download the script directly. Post the results.txt inside code tags. Copy & highlight the contents of the script and click on # in the edit panel above your post to auto add the code tags.
wget -O bootinfoscript 'http://bootinfoscript.git.sourceforge.net/git/gitweb.cgi?p=bootinfoscript/bootinfoscript;a=blob_plain;f=bootinfoscript;hb=HEAD'
chmod a+x bootinfoscript
sudo bash bootinfoscript
Boot Info Script courtesy of forum members meierfra & Gert Hulselmans
Page with instructions and download:
Paste contents of results.txt in a New Reply, then highlight entire file and click on # in edit panel(code tags) to make it easier to read.
Or You can generate the tags first by pressing the # icon in the New Reply Edit toolbar and then paste the contents between the generated [ code] paste here [ /code] tags.
V60 has improved formating and requires code tags to make it legible. New Version is a zip file that you have to extract to get .sh to run.
Install these before running script:
sudo apt-get install gawk
sudo apt-get install xz-utils