Add Editable Children

Navigate to https://app.remixfast.com/ and select desired app. This will open Visual App Editor.
Select Routes tab in Editor
Select Route you want to add Children to.
Select Detail Form view Route
Select Components panel
Select Editable Table component
Drag and Drop selected component at the bottom drop area
Select Related Item
Editable Children Added to Detail Form (Note: no separate route, detail route handles both main form and children editable table in a single action)