Odoo dbfilter allow many options like website-domain based odoo dbfilter, fixed domain filter, any database selection filter, etc…
In case we had database like awsmanager.snippetbucket.com, test.snippetbucket.com, snippetbucket.com
dbfilter = ^(test.snippetbucket.com|snippetbucket.com)$
Out of many database, it will pick only two database, similar modification can be done as needed.
Feel free to contact us for odoo requirements or server level support or odoo cloud services.