To extend the child case content display to show a table under each child case, you can make use of Preview/Open in new window. This will ensure that the Main table does not need too much of scrolling and expanding/collapsing.
As you have mentioned that the list of child cases would many in count, you can consider the preview approach to be a potential choice.
We cannot always have the same UI methodology which used to follow in traditional UI. Constellation needs the UI mind shift and choice of displaying the content in modern and efficient way.
To summarize, if you want a focused view of the nested child case table, you have three approaches
- Standard OOTB Preview
- Link column for each child case to open a modal window to view the table. For the link you might need to write a custom component for link to open a local action + view
- Focused preview with a custom component. Please take a look at the component developed for the same in the below link PDF viewer in a model window - Cosmos - #2 by JayachandraSiddipeta
I would suggest go for option 1
Regards
JC