If you want to add additional folders in the advanced search syntax query, then you will need the pipe | symbol to account for a folder name OR other folder name.  You can add as many pipes to your syntax as you need. Here's an example of this would look like.

{LF:LOOKIN="\folder path\"} & {LF:Name="<<folder name>>", Type="F"} | {LF:Name="<<folder name>>", Type="F"}