Here’s an interim solution:
Use a naming or tagging convention as @LucB suggests so that you can aggregate, e.g., via a Spotlight search, the files you want to include in a mutually meshed Hook group. Get the search results in a Finder window, select the files, then run @ttscoff’s Applescript for mesh Hooking Finder items (perhaps via a Keyboard Maestro Macro such as this one on the selected files). Executing the Applescript will create a meshed “Hook group.”
If you come across another file you want to add to the group, just tag or rename it according to your chosen convention, run the Spotlight search again, select all the files (which now include the new file), run the Applescript and it will Hook the new file to each of the files in the group.
If you want to attach a URL to all of the Finder items in your Hook group, copy the URL, run the Spotlight search, select the files, then run @ttscoff’s Applescript for Hooking a copied URL to Finder items (perhaps via a Keyboard Maestro Macro like this one) on the files. Et voila!