Add in-cell editing to Sub Grids with this new configuration from July 2016. Further enhancements to this feature will be coming in the future.
Note: Only single Multi Pick Fields and Yes/No fields are currently supported with this in-cell editing feature.
From the “Behavior” section of the Sub Grid Web part properties check the “Allow in-cell editing” option. This setting will turn the in-cell editing on for that sub grid only. Columns that are displayed on the sub grid that are Single Choice fields and Yes/No fields will be enabled.
Turn the in-cell editing on by clicking the in-cell editing button that will appear now that the feature has been enabled.
Once a change is made to any cell values the Save and Cancel buttons will appear enabling the user to save their updates.