The easy way around this I have found is to take a flash drive external hard drive or just another directory on your computer and place a copy of Sins 1.1... whatever the latest version is and then have entrenchment installed to a seperate directory and make a short cut to the sinsofasolarempire.exe from the 1.1 directory and rename it so that you know it is 1.1 not entrenchment. and from there you can launch 1.1 and the regular launcher will bring up entrenchment that is how I have 1.05 and 1.1 installed simultaneusly and it should still work for entrenchment.
Yeah, that makes sense but I run it through Impulse via digital download and that's a real pain. Glad to know I'm not an idiot & this is just something stupid on the Impulse/Stardock end. Makes no sense.