I did that, but again i stuck on loading screen when trying to connect to server.You click on the change settings button(looks like a computer, with a screw driver), then under the first option(MultiMC) & the first tab(features) there is two sets of option. You want the one that is FTB, and then you want to tick the box that says "Track FTB instances"
I have also notice that most of the time if I add a pack from FTB launcher and then try too load it with MultiMC it doesn't show up, all you need to do is hit the "Reload the instance list button on the main launcher(MultiMC).
When i created new world in single, it didn't even generated right world.