How do I make a mod with a dependency?

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.