A computer that is programmed with software attaches one object (“from-object”) to another object (“to-object”) by preparing a new duplicate of certain metadata in the from-object, without copying any content of the from-object. The new duplicate metadata is stored in memory for use in identifying the from-object and the to-object as being attached. If the from-object itself has any existing attachments, e.g. to a group of additional objects, there already exists a group of existing metadatas that form existing attachments between the from-object and the group of additional objects. In such a case, the computer still prepares, without content copying, a group of new metadatas to identify the relationship between a corresponding additional object and the from-object. Some embodiments also identify the to-object within each metadata in the group of new metadatas, thereby to identify a path of objects through which an additional object is accessible.