You might like to use gparted. Downoad the livecd and burn it to a disk and boot from it.
1) Then make the two partitions for your two new os.
2) Then right click on the partitions & under the manage flags option select boot for the two new partitions.
3) After you do so, install the two new os in the partitions.
4) (This is optional)But it might happen that your os does not boot anymore or all oses does not boot or only one or two oses boot. If these happens -
sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
- Press Enter.
sudo apt-get install -y boot-repair && boot-repair
- Press Enter
and select recommended repair.
Now, restart your PC and you are good to go.
Hope this helps you.