Row Grouping
Row grouping is a feature that allows a row to have children (usually notaded as __children) and it serves only the purpose of grouping the children with the possibility to toggle with a collapse icon.
This feature allows N-depth levels but the complexity will start depending on how much data/customization your cells include (we recommend to keep at maximum 10 levels or lower, Apollo is capable for N-depth as said but this can affect performance)