I have the same experience as QoC. Pre-check is not "inherited" as stated earlier above in my experience.
I have Global Entry and have always got precheck.
When traveling with my husband, he never got Precheck even though we were on the same itinerary/ record locator.
There were occasions when he was invited to go through Pre-check (even though BP had no precheck stamp) just as they were doing with other random passengers. But that had nothing to do with us traveling together since we were usually not next to each other as he got invited. And these occasions were rare (maybe once or twice that I remember of)
(Now he enrolled on Global Entry, so problem solved
)