How to replace text with \n using regex?

Hi All,

We need to replace it with new line with the same number of new line occurrence in source file. Example below..

**************
john< !-- New Line Here in SOURCE for your reference -->
< !-- New Line Here in SOURCE for your reference -->
="878">macky
**************

**************
john
< !-- New Line MUST be retain in TARGET for your reference -->
< !-- New Line MUST be retain in TARGET for your reference -->
macky
**************

Thanks in advance.