This can be done only with permission from the creator of the prerequisite mod. You may think that simply giving credit is enough, but a lot of people disagree. Mod authors have the ability to decide whether their mods can be used freely or not, and redistributed or not. Sure, for some, restricting the use of their assets may be for vanity, they want their mod page to be seen and noticed, but that is far from the only reason to do this. For example, let's a mod were updated to fix a number of bugs, add new features, increase performance, etc, and that mod had been a prerequisite for several other mods. If those other mods had included that prerequisite within their own downloads, instead of directing users to download the prerequisite from the source, then from that point on, anyone downloading one of those mods would be getting an out-of-date version of the prerequisite, until such time that the other mods' authors updated their files. This creates potential problems for users, encountering bugs that have since been fixed, and mod authors, potentially getting blamed for issues that have already been fixed.