Homebrew Citra dlc and cia help

[Salad2001]

I was wondering if there is a way to make a cia file, like a game and it's dlc into one to decrypt and use that one file. also how would i decrypt a cia and is there a way to make already installed cia's back into them

 

[Quantumcat]

For the last part, see https://3ds.guide/godmode9-usage under dumping a title.