Triple-boot Win8x, Win10x_WI, & Win10x

[JediTWang]

About to have a crack at this tomorrow,

Have already set-up the size partitions I want* using the tool provided in my Win10 boot/install USB, & have already installed Win10x.

Tomorrow I'll use my SP3 Recovery USB to install 8.1 ("use existing partitions" option), then once done I'll again use the Win10x boot/install USB to install Win10x_WI (fast) on the 3rd partition I've created.

Don't have time to go into all the detail just yet, just wondering if there's any "gotchas" I must avoid? Has anyone successfully done this already? Google search revealed nothing for me >.>

I'm aware of the possibility of running 1 or more of these environments in VM's, but I'm not interested in that approach ATM, so please stick to the topic.

Thank-you.
*~142GB for Win8x (this will be used fairly heavily)
~110GB for Win10x_WI (this will be used lightly, only when there's a major build released, won't be installing heaps of 3rd-party sw)
^For some reason these 2 didn't hit the sizes I wanted, both ended-up up being quite a bit smaller -but they'll do I guess
330GB for Win10x (this will be the main partition, & used much more than the other 2)

 

[JediTWang]

Anyone???
Ran out of time today, hopefully will have time to delve deeper tomorrow or the next day.

TY.