Never underestimate the supernatural and go with your gut, and be objective in your approach. Most will say this feedback is over-the-top, but the amount of details your child can provide along with your own concern, may indicate something else is going on. While your child may have an active and detailed imagination, some of the details you outline are too coincidental to involvement with the supernatural. Regardless on your faith (even being agnostic) and what you see on TV, approach your situation as a fully informed person. Begin by keeping a journal of her imaginary friends. Write down names, relationships, details, clothing, and facts. Your child may have a wonderful ability of seeing those who are to come, or those who have gone, or those in a parallel realm. In either case, gently ask her for as much detail as you can as part of normal conversation and jot it down. Along with such an ability comes responsibility, especially interacting with those who would do harm or even suggest harm. As you have rightly done, you've told your daughter that she has complete control over who interacts with her, which is oh, so true. The journal acts as your proof and, if nothing else, acts as a great way to reminiscence in later years.
No, she's not possessed or anything like that, but she may just have a keen awareness of the supernatural. Some are just born that way, but you need to approach with reasonable caution. Your approach thus far has been great. Continue to monitor and be informed by tracking her interactions in a journal. You may want to follow up and see if such folks really exist or existed. If you find that some or most used to live in your area, then you'll know for sure.
The only time you need to be concerned is when the imaginary friends begin interacting with your world, e.g. when she begins blaming them for doing things, or when items in your house are being moved, broken mysteriously. If this does occur, don't automatically blame your child. It may truly not be her fault. Again, objectively find out the facts. Let her tell her story. You'll get a sense of whether or not she is telling the truth or making up stories - e.g. when the description of the incident rolls off her tongue versus when she pauses or gives a pensive look as she is making it up as she goes.
Our daughter has an active and detailed imagination as well. It is based on her stuffed animals. Each has their own name, all have a complex family tree whereby one stuffed animal is related to another, and each one has their own specific diet. Again, there is consistency in her memory so you'll get the same response now as you did two years ago. What we did was to openly talk about each animal and incorporated as part of our normal conversation and family life. We even created a collage of her stuffed animals and a visual family tree. Perhaps you can do the same. Sometimes it's just your daughter wanting you to incorporate yourself into her world, so she feels connected and secure, versus getting frustrated at her or expressing your concerns about her 'friends' to her. Accept them, find out what you can about them, 'interact' with them (be proactive in this, ask to talk to so-and-so, and attempt a rue conversation, ask questions as you would an ordinary person - where do you live? What do you do? Are you student? if so, where? Do you like playing with my daughter? What do you like to do? What do you hope to do?), and engage in your daughter's world by incorporating them into your family conversations. Encourage dad to do the same. It is especially important that dad be actively and pro-actively involved in this. Much of your daughter's responsiveness to this will be based on what dad thinks and does. Talk it over at the dinner table. Embrace it, be informed, track it, and then make your assessment.
Best of luck and let us know your progress!
