windows - How to dual boot (Ubuntu-Win) with Lenovo U41-70? - Issue with partitions and recovery

My Lenovo U41-70 (i7-5500U) came with a licensed Windows 8.1 (upgradable to Windows 10) and has by default the following partitions:

1. ~1000 MB (Recovery partition)


2. ~260 MB (EFI system partition)



3. ~1000 MB (OEM partition)


4. ~13 GB (recovery partition)


5. ~25 GB (Primary partition) - D: drive called Lenovo to store data


6. ~900 GB (boot, page file, crash dump, primary partition) - C: with the OS installed

It has a recovery button/software which allows you to recover the original OS, namely the Windows 8.1 but I didn't get any Windows installation disk. The problem is that this recovery software seems to work only if the original partitions are untouched. Therefore if I create a partition for Ubuntu or for keeping my data separated from the OS I will lose my licensed Windows.

My question is: how can I install Ubuntu and create 1 or 2 data partitions without losing the possibility to reinstall my (licensed) Windows?

The recovery software installs back Windows 8.1 but I actually use Windows 10.