I just thought of something......Dillon is rich, right?
Say Church is Sandman and Grace is Electro...possible plot detail:
Dillon is a spoiled brat, rich boy taking over a company that researches weapons, he thinks he knows everything, and in his stupidity, he alters something out of one of the programs. One of the workers in his place is (I forget Sandman's name, Baker I think, so I'll use that) Baker, who is doing something with sand. The building gets messed up and everything seems to go down with it, but in the process, Sandman and Electro are created. Possibly make it so this happens as a last result, when Spider-Man exposes that Dillon and them are doing bad things in the research facility, so they do that screw-up step in an attempt to finish their project before they're exposed fully. Then that happens and they take it out on Spider-Man. Dillon himself is rich, so he can attract to Mary Jane if they really wanna go that route, which I think would be stupid, but you know. Sandman could be more of the muscle, and Electro could be the brains. If they both work together in the same company, they could work together as partners...and it wouldn't seem odd like the Mr. Freeze/Poison Ivy combination or anything.
Whammo, there's a story I'd like....much better than 2 people playing Chameleon.
Maybe you can kill off Sandman, and arrest Electro. Or somehow when you kill them both, make it so they affect each other in some way and that's how they die. Maybe put them inside of water, Sandman disperses while they're both getting electrocuted and whatnot.