I can't find the article now, but one study had extensive interviews and questionnaires given to one woman's mother before she died. This also included voice samples to reproduce her voice.
After the mother's death, the woman was able to have "conversations" with her mother about various things, including advice. An interesting side-note is that the woman actually learned some things about her mother that she hadn't known before, because there were things that the mother felt comfortable telling the researchers things about her life that she wouldn't discuss with her daughter. However, given what I've learned of AI of late, I wonder if any of this "new" information had not simply been made up...
This could be mentally unhealthy, I think... I'm sure there are more than a few stories that could be written about this subject... In fact at least one already has, written a few decades ago... "The Light of Other Days" by Bog Shaw.
Huh, the story is online... not sure how legal that is, but it is definitely worth a read, IMHO.