I hope you work with paragraph styles, you should do so, use 2 paragraph styles.
Make for each line its own paragraph, in the paragraph style set the other style as next style.
To adjust the distance make changes in the paragraph styles in space before and after.
Never use any double return to force space between paragraphs, work only with space before and after.
We need to see this with non-printing characters showing, and need to know how many paragraph styles are being used.