SharePoint 365 Restrict subfolder access requests

Question

I control a sharepoint site for a group in my company. Within this sharepoint is a number of Document folders, each with their sub-folders.

The problem I'm having is whenever a user copies the URL for a sub-folder and sends it to a new user. Their permission request is for that sub-folder or file only.

This creates a dilemma. Either I reject the request and manually add them to the correct group, which normally causes the user to be confused about getting their access denied. OR I accept the request, giving them read only access, still manually add them to the correct group, and then need to go through the site permissions deleting the newly created "Unique Permissions" for the sub-folder/file.

Answer 1

Extra bit of information. When the new user requests permission for the sub-folder. The list of available permissions that I can provide to them DOES NOT include any of my groups. It only provides a list of default permissions. (Read/Contribute/etc..)