"The only way to get more control over the line spacing is to set a fixed value."

That cannot be done when one is using two dramatically different fonts each having different space requirements. The roman font needs 1.15 line spacing, whereas the Hindi font needs 1.25 line spacing. And this differential has worked wonderfully throughout the book. The problem I have described in this thread -- that I cannot get the four line poem to start on the top line of the page 174 -- does not seem to have anything to do with their being different spacing settings for the Hindi and Roman fonts. The entire 330 page document has worked beautifully with the differential line spacing.