Created Folders Do Not Inherit Permissions From Parent Folder

I've got a problem with my CentOS/CPanel server, and its driving me bananas trying to get it worked out. User1 has a subfolder called Uploads somewhere in its directory that he should be sharing with User2. I have chmod-ed Uploads to 775 and placed User1 and User2 in the same group so that User2 can create folders in Uploads and put files in those folders. When thumbnails need to be generated for my site, User2 creates a subfolder in Uploads called Thumbnails, and then writes the resulting thumbnail images into this folder. The /Thumbnails folder is created with 755 permissions. This makes it so that when User1 tries to add its own thumbnail images to the /Thumbnails folder, it is not able to. I have managed to configure the default folder creation settings so that this /Thumbnails folder belongs to the Group that User1 and User2 share at the time of creation. However, I can not for the life of me get the configuration right so that this folder is generated with 775 permissions. I have read this forum post: [url=http://www.linuxquestions.org/questions/linux-desktop-74/applying-default-permissions-for-newly-created-files-within-a-specific-folder-605129/]Applying default permissions for newly created files within a specific folder and anything related I've been able to find on the net. I have done everything I can think of / find in order to set default folder permissions, but no matter what I do the PHP script that generates the /Thumbnails folder is creating it as 755. As a side note, when I create a folder manually using the file manager in CPanel's UI, it also comes out with 755 permissions despite being created as a subfolder in a folder with 775 permissions. I'm sure there is some simple setting somewhere I'm missing. Any help you guys can offer with this matter would be greatly appreciated. Thank you.