Trouble adding mods to modpack

[Dude36_HD]

So I got Unabridged for the mass amount of mods to play with my buddies, but I wanted to incorporate industrialcraft 2 as well... thing is I had already started a server. You know generated world and things. It's giving me the error message that of course there's missing blocks because something new was added. I just want to know if there is a way to just go on without the blocks it wants to add to the already generated landscape. Or if there is a way to alternatively start the server with an "fml" command, something along the lines of that. The console tells me I can alternatively start it to go on without the blocks, I just have no clue to go about doing that. Help as soon as possible would be greatly appreciated I check for responses daily. Thank you for your time.

[larsgerrits]

IC2 has something called retrogen, which means it will be able to generate ores and trees after chunk generation, which may fix your issues. You just have to enable in in the configs.