How to write data from a xaml file to another xaml file without overwritten?

Help
1

I have tried the Write Range Activity but it overwrote the target file.

2

if is it ok, then try like this.
read the text before you write and store it on a variable
concatinate the new string with the variable.
then write the new variable
like this
a = "old text"; b="new text"; write(a+b);