The only asset relations that are automatically created are the ones between Windows computers and their monitors. VMware/Hyper-V hosts and their guests as well as switches and their connected assets are linked as well, but not with the asset relation feature.
Having other asset relations automatically created is on our customer wish list, but we do not have a release date for this feature. If we understand correctly, you would like to automatically link SQL databases and/or SQL instances of guest machines to hosts, which is not currently possible. You could certainly build a report to list your hosts and their guest databases. Though this is not something we can provide instructions or support for, you could also write a custom database script based on the tblSqlServers, tblSqlDatabases and tblAssetRelations database tables to create assets for the SQL databases or instances and link those to the hosts. Scripts can be run manually under Configuration\Database Scripts or scheduled with external SQL tools. We recommend backing up your installation prior to running any scripts though, by following
these instructions.