For if you wanted to play a pre- existing mod pack, but with a few tweaks or changes to make it suit your personal tastes. You currently have to look at the mods list of the pack, then track down every one of them and put them into a mod pack you created in order to edit them.
^^ Claycorp with the answers!
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Download the pack
Click the ... button in the top right next to play
Click "Profile Options"
Check the box by "Enable Content management for this profile"
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