There is no built-in functionality at the moment to link a document to multiple assets at once. This feature is on our customer wish list, but we do not have a release date for it at this time. This is not something we can really provide instructions or support for, but you could upload the document to 1 asset and then insert the remaining links to the other assets directly in the tblAssetDocs database table. (This table only stores a reference to the file. The actual file is stored in the Program Files (x86)\Lansweeper\Website\DOCS folder of your Lansweeper installation, not directly in the database.)