I'm going to convince two of my depressed friends to date only to convince them to break up a few months later
Why would you do something like this?
I think if they are already depressed it's can't get any worse.
If they are your friends you should do stuff to make their life better not things to make them worse. You need to be there for them. If they would be good together that is a good thing, but breaking them up would make them even more depressed.
It's totally fine since they will find love again.
It is very wrong to hurt people who are depressed. I think you should try to find them mental help if they need it and not get them into a relationship complicating their issues.