Another tip on how to get the regex for a selected block.
Open one of the files that contains the multiple lines (multiline) to search or replace.
Click Ctrl+F and select “Regular expression”. Close the Find/Replace window.
Select the block you need and click again Ctrl+F to open the Find/Replace window.
Now in the Find text box you have the regular expression that exactly matches your selection block.
(I discovered this, only after creating manually a regexp for very long block 🙂