Antlr4 add new node to tree

I am working with antlr4 to create a tree from cobol code and my main objective is to add new code by modifying tree. Are there any way to modify or add new nodes to the tree and generate a new cobol code from this new tree?

For example, If I have a cobol code with

DISPLAY "Hello world!".

I want to modify the text "Hello world!" or adding a new node with the code

DISPLAY "Hello again!".

And from this, generate a new updated cobol code from this new modified tree.

Thanks in advance!