You can use {ni'o ni'o} for a second level of separation,
{ni'o ni'o ni'o} for a third level, and so on.
You can also use {tu'e <text> tu'u} to bracket a whole text,
so for several texts you could just say {tu'e <text1> tu'u ni'o
tu'e <text2> tu'u ni'o tu'e <text3> tu'u}.