HI Amish - I think what you might be asking for here is twofold: (1) A formal account delegation feature (besides just giving someone your account username and password credential), and (2) a visual cue that such a delegation is in place, such as in Outlook when you receive a message from someone "on behalf of” someone else? Am I right?
Neither of these is available OOTB, and I'm not aware of a customization available for either 1 or 2.
BUT! Aurea PS has an add-on called "Delegate Access Module” available for purchase that allows designated users with this permission set to be a "Ghost writer” / "forge” a post as if they were someone else. It's a bit of a convoluted process to achieve it, lots of steps and gotchas, but check with your account manager.
 We have this module for use by executive assistants and executive committee members who have their own communications teams.
As part of our process to use this module, I require folks to (1) mention the author at the bottom, and (2) mention themselves immediately afterward with a line "Published by: ".
I'm old fashioned like that. I get it when you have a typist or a document preparer like the olden days, and i expect something like initials MO:mo to signify the same (Author/Publisher).
At present this is a manual process, though I wish it could be baked into the module.
Hey Mike .. Thanks you very much for this reply and providing the additional details. I really appreciate this.
What you have interpreted from my questions is accurate, especially for # 1.
The "Delegate Access Module" may work for our needs but to a less extend. However, I am still going to share this information with my team and especially, with our internal customer who has requested such feature. Coincidentally, she too is an Executive Admin Assistant!
One again, thank you!