Associate BAK file with SQL Server database
This bak file is not recognized as belonging to this database


It may just be that you haven't performed a tail log backup on the target database.  But you should restore the backup and all the log files to a new database first to determine if it has the data you need.  Then you can either proceed with the restore, or manually copy the data from the new database.


  It was my assumption that I could use the LDF in conjunction with a BAK to reconstitute the database at any given point. Does it not work that way?


No.  The LDF will be overwritten in a restore.  You must move the transaction log records from the LDF to a log backup first.  That's why RESTORE over an existing database will fail if you haven't taken a Tail Log backup: otherwise you would lose data.

So before you start the restore sequence, ensure you've taken a Log Backup of the database.  This will move all the log records currently in the .LDF file into the log backup file and make them available for use in a point-in-time restore.