I know this will probably be in the next version but I could make good use of such a script now.
I could be wrong about such things, but I think it's very unlikely to be in the next version.
I found the script and I would be happy to send it to you. But it's a very complicated SQLite script and a very long SQLite script for a first try at running such a script. Also, it's pretty rough and unpolished, not like I prefer scripts to be if I'm going to share them.
It first adds a Parent fact to everybody who has parents, provided the person has some sort of valid birth fact. The reason for this restriction is because it needs to add a date and a sort date to the fact being added to place it right after the birth fact. Dealing with the dates is one of the most complicated parts of the script, and I stole some code from Tom to get it to work correctly.
It adds both the father's name and the mother's name to the Description field of the same fact, which is not quite what you want to do. It probably wouldn't be too hard instead to add two separate facts, one for the father and one for the mother.
Finally, it does the sharing of the new fact with the parents which I described. That part is tricky as well, but it sounds like with your use case that the sharing would not be necessary.
I could add the script to Tom's wicki or I could get it to you in a more direct manner. Given the forthcoming transition of Tom's wicki to a new site and a new technology, he may not want anything else added to the old site at this time.