Quick update on what's been happening since I started this thread:
I think I manage to help the ghost in my home cross over! I'm not sure yet but I definitely felt her actively trying when I did my best to open a portal for her. I had a few of my spirits help me as well of course! Tbh, it was kind of much easier than what I thought. Went into a meditative state in front of my altar, invoked my spirit guides and companions, visualized the light, and encouraged Monica to cross (that's what I understood her name was). I had to try twice, the first time it seemed she couldn't see the light, the second time I was a little bit more precise in my visualization and actively directed her towards it. I felt really strong shivers, the kind I get when a spirit is close by, and then, pouff, nothing.
I asked my spirit friends if she had crossed and they said yes. I also don't feel much activity around her vessel anymore. I'll see how it goes in the next few days, and maybe I'll try another pendulum session to confirm. I really do hope I managed to help her! It was a pretty fulfilling experience overall tbh
