You have to try it but I think it still works. Aliases just replaced the text you typed with text in the alias, so if you append a subfolder to the alias it should also be appended to the command.
It's like using !! when navigating folders. You can do cd ~/Downloads and then !!/source and it resolves to cd ~/Downloads/source
I'm sure that still works with aliases. Then you'll have dl/source and Doenloads/source that are the same location. Using aliases will mean any script or program you may use that might point to them won't just create a new default folder that is then no longer the same location as the renamed one that you'll expect everything in