How to create multiboot system using different single partition installations

Hi,

I am familiar with multiboot systems and have create them by installing different operating sytems one after the other (winXP then win7 then ubuntu) and then imaging everything with acrois true image 2014.

I have to do something different this time...

This is what I have done:

I wiped a hard drive clean.

I created an empty boot partition and installed win7.

I used acronis true image 2014 to create an image of win7.

I then ran an upgrade from win7 to win10.

I used acronis true image 2014 to create an image of win10.

I then wiped the drive and created a new boot partition and installed ubuntu.

I used acronis true image 2014 to created an image of ubuntu.

I can switch between booting into  win7, wn10 or ubuntu by wiping the boot partition, creating an new boot partition and then restoring the OS image I want to boot to that empty partition - and set toe boot flag.

It works every time.

Is there a way to restore the win7, win10 and ubuntu installations to three separate partitions and create a multiboot system?

Big thanks.

Mike