Can someone please explain how groups of notes can be grouped into a phrase?
Is it possible to group more than two notes with the 'slur' command without misplacing lyric syllables?
You can slur as many notes as you like. Just highlight all but the final note, then apply slur. Be sure that you use slur, rather than tie.
As you observed, the slur changes the way that lyrics are associated with notes. No problem. Highlight the intermediate notes, right-click for properties, and ensure that the intermediate notes have lyrics syllables "always." That will change the slur (which only uses one syllable for a group of slurred notes) to a phrase (which may have a syllable at each note). You can also do mix-and-match, with some syllables extending over more than one note.
Many thanks Robert A for your speedy response.