[HELP]ME3 - Gibbed Save Editor - Suicide Mission and Normandy upgrades

Try this: ME3 Plot Database.

It has a list of codes for various things. In Gibbed, you have to go to the "Manual" section. Under Bool you'd want to insert, say "39" for Thane, and hit "get". If it says that it's set to true, that means the person is alive. Hit "set" and it should change the flag to "false". That will make the person dead. This isn't the most comprehensive database I've seen but you can google to find more.

Or try this one: ME3 Explorer Toolset. It has specific plot id numbers to set people as dead. I see you probably know that two have to survive in order for Shepard to be alive. I actually have one set with only Zaeed set to be alive but I don't know how that will turn out.