One possible solution:    Enter the windows system ,    install    EasyBCD, in this software , there is one function that anable you to recover the MBR of windows system. You can have a try ,be sure to backup before you   start.

backup first.
in windows, use windows built in disk manager to spare a parition, no need to format.
when you install deepin, it will find that empty partitaion and ask you if use it, yes.
in bois disable security boot and use uefi
when installation finished, you will see a menu at startup let you boot either linux or windows

Edited by nooban at 2018-6-3 23:32

Hello,

thank you both for you responses.

https://bbs.deepin.org/user/111488 Thank you for info about easybcd, will be usefuil.....I will use easyBCD once i manage to install deepin, after i figure out how to actually install it without affecting my primary OS(windows7)...

https://bbs.deepin.org/user/50118 as you suggested, in windows disk manager i did the shrink on my existing partition. Now i have 64BG of unallocated space.
Regarding UEFI, this laptop is older and doesnt have this option in BIOS......Can i use deepin without UEFI?

if you computer does not have uefi, then it is even easier to install dual systems, just use the free space for deepin, after installation you will see the menu as I mentioned.

Install deepin in a existing windows with a linux partition ,if windows not display in boot menu after install deepin,you can run a 'sudo update-grub' command in deepin terminal, can find windows system and add in boot menu.