change-log-merge
change-log-merge is an interactive autoloaded compiled Lisp function in `add-log.el
'.
(change-log-merge OTHER-LOG)
Merge the contents of change log file OTHER-LOG with this buffer.
Both must be found in Change Log mode (since the merging depends on
the appropriate motion commands). OTHER-LOG can be either a file name
or a buffer.
Entries are inserted in chronological order. Both the current and
old-style time formats for entries are supported.