Option to automatically copy and delete elements in child tables is option set "has parent".
At this time, we can use own DCA snippet to realize this function - maybe we can add this and select with checkbox
$GLOBALS['TL_DCA']['mm_events'] = array
(
'dca_config' => array
(
'data_provider' => array
(
'default' => array
(
'source' => 'mm_events'
),
'mm_event_dates' => array
(
'source' => 'mm_event_dates'
),
),
'childCondition' => array
(
....you would have to develop a configurable system
@discordier: maybe we can just add a checkbox in the configuration of the input mask - there the model is defined as a child table...