If we open create form Dynamics 365 Online of any entity, for example, accounts, we see, that instead of sub-grids (opportunities) with related records we have empty sections. On update form these grids are visible. When we used CRM 2016 on-premise version, sub-grids of related records were present on create form with a label: "To enable this content, create a record". It would be great, if the same behaviour was on Dynamics 365 Online version.