If your motherboard has Uefi firmware then you will probably find it next to impossible to achieve, certainly more trouble than it is worth. Most likely though you will have a normal bios (because you already have MInt14 installed and I don't think you have contributed to any of the Uefi disaster threads). In that case the procedure should be simple enough. Grub should look after itself. If you install it to the disk mbr -/dev/sda - for example (usually this is the default setting) it will change the grub you see at boot to whatever operating system you have added, but the newer grub will automatically include the Mint operating system in it.
The devices mounted through fstab can be set from within the installer usually, but it is not always obvious how to do it. Your new OS will write into fstab what it needs to boot automatically. Anything else you may need to do manually but it isn't difficult. For example here is an entry that adds Mint to my Ubuntu fstab (so I can access the Mint files when using Ubuntu):
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LABEL=mint /mnt/mint ext4 defaults 0 2
Items to note are that I use partition labels to identify my partitions in fstab. This is not the default, usually you will see something like UUID=71ad6514-32a7-42ab-83d8-edbfdfc122fe - but I know which is easier to read

Secondly the folder /mnt/mint has to be created manually before the entry will work and thirdly, not all filesystems are ext4, but I am sure you can find your way around these options yourself.
Good luck anyway.
Oh and if you are installing Fedora make sure it doesn't install in LVM mode - this used to be the default and is fine if you understand logical volume management but if like me, you don't, you will want to switch this option off (they may not do this any more it is quite a while since I installed Fedora).
Fujitsu Lifebook AH532 Laptop. Intel i5 processor, 6Gb ram, Intel HD3000 graphics, Intel Audio/wifi. Realtek RTL8111/8168B Ethernet.Ubuntu12.10 (Unity), Mint14 (Cinnamon), Manjaro (Xfce).
