Install different version of IW

First let me say that I think CG Dev Tools is DEAD and their source code version, in it present form, requires the licencing DCUs to be compiled with nthe latest Delphi Version and I am unable (for six month) to get CG Dev Tools to respond.

So I want to convert some of my apps to IW/Bootstrap.

I have both Delphi 11.3 and Delphi 12.1 installed on my computer.

QUESTION:

How do I keep my IW 15.4.1 installed on my Delphi 11.3 - for CG Dev Tools maintenance 
AND
Install IW 15.6.2 installed on my Delphi 12.1 - for Bootstrap development 

TIA