Hi Cristie,
In addition to Alice's response, the Kinetis bootloader 1.2.0 was compiled and tested with Kinetis Design Studio v3.0.0, so I would recommend you to create a new environment in KDS 3.0.0 to work with KBOOT 1.2.
Regarding the installation of KDS 3.0.0 and KSDK1.2.0, you can have both versions of KDS and both versions of KDSK installed in the same machine without any problem, I would just recommend that you make sure that the correct version of KSDK is chosen when creating a new project:
For KDS 2.0.0.

For KDS 3.0.0.

About the procedure to install KDS and KDSK, please take a look to the following video:
Video Link : 3281
Hope it helps!
Best Regards,
Carlos Mendoza
Technical Support Engineer
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