Creates one or more URL-prefix properties in Google Search Console (Webmasters sites.add) and registers them in GSC Wizard. Use this to add folder-level properties (e.g. https://example.com/blog/) that do not yet exist in Search Console. They are auto-verified if the connected Google account owns the parent domain property. parentSiteUrl is an existing GSC Wizard property whose Google account has access; the new properties inherit it. Every property URL must be under the parentSiteUrl domain (that domain or a subdomain of it). Created properties are added hidden and consume no plan slot until you show them with set_dashboard_visibility, which enforces the dashboard limit. For properties that already exist in GSC, use add_site instead.