I want to triple-boot Lion, El Capitan, and WIndows. Howto? I have a late-2011 MBP that currently has two operating systems on it. Those two operating systems were Windows 7 and Lion, for a long time. However, I have to use Yosemite (or newer) for some applications for work. So I blew out my Windows partition and set up Yosemite on it. 

Now, I want to install Windows again. However, 100% of the triple-boot tutorials I find assume that I want to install Linux as my third OS, so I can't just follow someone else's recipe. I recall Core Storage hassles when going back and forth between Yosemite and Win7. 

What's the best approach for me? I can't use Boot Camp, because I already have the Yosemite partition. Should I blow out Yosemite, repartition to have one full-disk Lion partition, use Boot Camp to install Windows, and then... something else?
iPartition used to be the go-to tool for this kind of task, but it cannot handle Core Storage volumes, which makes it a bit limited these days.

Paragon have just brought out a new Hard Disk Manager which I have yet to try out for myself, but looks like it's the long-awaited successor to iPartition. Personally, I don't think the interface looks as good, but you can't have everything ;-)

Both apps require you to boot from an external device to work on the boot drive, of course. Paragon has a built-in boot drive creator, I can't remember whether iPartition does [it had a CD maker, back in the day, but I've not used it in quite a while]

For your particular scenario - I'd clone off one of the Mac partitions, re-partition as a single Mac volume [plus EFI/Recovery of course] then let Bootcamp do its regular setup. Afterwards, resize then add a new partition to clone your 2nd OS X back to.