How can I change the data displayed in MyTreeBuilder or add display conditions?
The $segments property works basically the same as the $columns property in tables. And you’ll need to use a callback to control the models returned if you have conditional filtering needed.
How to save data to two tables in the database when creating a new object?
Let's open a new discussion about this one with an example of what you're trying to do exactly (ie, two streams I assume?)