I have yet to Replay Fallout 2 as I don't have copy right now.
I just remember the Salvatores having Lasers as their main offense and that they were coordinating with the Enclave (possibly obtained Plasma tech from them as well.). Also, the head Salvatore was a decrepit old man who needed a respirator. I also remember most of his bodyguards were black.

Here's a theory:
The Salvatores are destroyed when the Chosen one passed by New Reno.
Either killed by the Chosen One or not, Louis Salvatore passes away with no one to pass his possessions onto.
Here is where the Van Graffs pop in. 'Mother' Van Graff is somehow able to take over Salvatore's business growing even stronger with the acquisition of Plasma. Mother Van Graff herself is possibly related to one of the bodyguards. One of them possibly planned to assassinate Old man Salvatore but Chosen One did that himself possibly killing all guards in the process though one of the guards was able to tell Mother Van Graff the plan before dying.

I know it's farfetched. This is what insomnia does to you. Connecting dots in your head...