Hi αlτεrηιτγ,
Thanks for taking this so seriously, but not sensationalizing. I mean, who am I to say thanks, but thanks. I think when we approach topics like this calmly but with focus, more gets done.
Sometimes after a soul retrieval, people will become agitated, or experience agitation in their surroundings. While I have no idea whether this is true for your friend or not, sometimes this happens because an entity with a person (one who has previously been comfortable dwelling within the person) is interacting with the energy of the returned soul part, and is not comfortable with the new state of health of the person. If this were the case, compassionate psychopomp work might be called for. While I hate to say any one thing or another is 'advanced work - do not try at home', I will say that there are risks involved with psychopomp work for sure.
If there were an entity with your friend, again, may or may not be, the work would best include helping that spirit get to where they need to be in a manner which causes no fear, anger, alarm or shock either for the entity or your friend.
The banishing ritual of the petagram, that is very similar to calling in the directions, right? But with specific angels? (I don't know if I am remembering right, I just use calling the directions). I think both practices are somewhat symbolic for establishing our own alignment in time and space and dimensions as well as requesting spirit aid. I don't think anything ever can come of that which is not beneficial, if practiced with calm, strong and focused intent for empowerment and wholeness.
The soul retrievals I have been a part of, they have been uniformly touching and beautiful. I don't know what I could share that you could not read on your own, but perhaps how important it's been for me to do my own diligent work on myself, and to keep my focus so crystalline and unwavering when doing that type of work, start to finish. I also only attempt the work when I am feeling strong, and when I know I have the help of spirits who are interested in the positive outcome of healing.
Something I have found beneficial for people, which likely helps them retain that soul energy and move forward with it, is to also bring back that person's animal ally, when available, and when appropriate. Something else I have found beneficial is that after the return of an ally or a soul part, that I allow the person to sit with it while I rattle, drum or sing. A lot of work is going on with this, but simplistically, I am sealing it in, helping to 'lock in' the new position.
There are many ways to look at what we are talking about, of course. I happen to be using the cosmology of shamanism in discussing. Ya? Ya. We could use psychology, alchemy, taoism or any of a number of ways to talk about the same things. But shamanism has been effective and useful for thousands and thousands of years, and I find it very comfortable.

That underworld you are talking about, I think in some systems this is what I call the 'middle world' which is where we find all so many different beings, including ghosties and such. I will read more about the term.
There is also, in some systems, the 'lower world', which is safe and earthy, and generally populated with spirits appearing as animals.
They tend to bring power, protection and insight, and imho that is invaluable to a person when doing the hard work of integrating soul parts. If your friend is open to it, and the spirits are open to it, perhaps she could explore with you bringing this help into her life.
I was taught certain steps and certain ways to do all this work, and it's taken years. It started with me working the same on myself first, and ended with me running off to the woods for a year where I met some amazing people I lived with for a time, beneath the trees. I say this, as I don't really know how to condense all of what I've learned into a post, but you did ask, and I do want to share. ;P Feel free to pm me if you like. I'm sure we have stuff to learn/teach from each other.
Do you take intentional 'journeys' when looking for information? Are you aware of or do you call on your own good guides and allies to not only keep you safe but inform you of steps you might take? You certainly don't need to answer this here. I ask because often the information on what to do and how best to do it can come from those beings, much wiser than me. It's been very valuable to me to work on my relationships with the spirits who work with me, to the point where that is where I go first for information.
Do you remember your healing dreams? Sounds like there is a lot of good information there. Anything in the dreams you can bring back and replicate in waking world?
Your description with the quartz wand sounds like you have an instinct for this. Of course you do, lol.
When we help that energy move and rise, we get to be very aware of what it causes/creates/makes room for in the person in front of us. We are messing with the status quo when we do healing work.

So, part of every work I do is to get the person's permission, and then proceed with care and focus, and if I get muddied or unsure, I redouble my effort on being open, without ego, clean, and in service. So many spirits willing to help someone with this posture. Also, I find the energy of 'gratitude' creates an environment inhospitable to negativity in any form. Emotions are excellent tools as well.

Thanks for the opportunity to talk on this, and thanks for the work you do.