How do I make a mod that uses a dependency?

Just to repost this from OrphanedPixel's Question That I also have (stopped being commented on):

"I'm currently trying to make an addon for a mod I like for private use (though if I get the creator's permission, I may release the addon publicly). However, I've run into a problem in which Mcreator won't let me compile a mod with a dependency. Is there any way to get around this? If it's of any help, the errors lie when I try to import parts of the mod and have a block drop items from the mod."

I currently want to do the same thing (except for the part on uploading it) and I need things from that mod to do it.