Submitted by: Matt Dowle; Assigned to: Nobody; [R-Forge link](https://r-forge.r-project.org/tracker/index.php?func=detail&aid=2590&group_id=240&atid=975) As raised [here on SO](http://stackoverflow.com/questions/15096811/why-is-using-update-on-a-lm-inside-a-grouped-data-table-losing-its-model-data). I had a look and made progress but couldn't for the life of me work out why the last group is reused.