The reason I have created this topic is that I don't want Cass to die and I don't want the Van Graffs to die and I would like to continue with the quest.

I've tried a different combination of console commands and all i've managed to do is complete the objective but I have not been able to move on.

Any help will be much appreciated.

Be careful, this could cause bugs later on. I would more recommend that you make a seperate save to try them out and just keep track of that save so you don't overwrite it.