There shoud be the option to add an expiriation date or -period to files, that are shared with single persons only. The file will automatically move to the recycle bin after the expiration time and be processed as usual (extinction after defined period of time)
Since you've already installed HCL Connections anyway, this would provide you a sort of cloud function for files that are supposed to be shared briefly. That's it. No furhter editing in communitys.
The feature reliefs you from additional efforts to delete shared files (see for example feature in nextCloud). See also: https://docs.nextcloud.com/server/19/benutzerhandbuch/files/access_webgui.html