Manuia - be happy, lucky, successful; ia manuia - cheers, to your health (pertaining to kava drinking or raising glasses to someone or something); fa'amanuia - bless, wish good luck; fa'amanuiaga - blessing, good wishes.
Good Morning
May you have a blessed/happy 16th birthday. Blessed is manuia; happy is fiafia.
Goodnight - "Manuia le po", "Po manuia" or "Po lelei".
Manuia le malaga; malaga manuia
If you mean goodnight, it's manuia le po
"Po lelei"; "Po manuia"; "Manuia le po".
Manuia le uikegi = Have a good weekend or Manuia lou uikegi = You have a good weekend
Manuia le
Manuia le Kilisimasi ma maua se Tausaga Fou fiafia
Manuia le po = Have a good night / Goodnight.
"Manuia le afiafi"; "afiafi lelei"; afiafi manuia".
Happy Children's Day. Edit: "Ia manuia le aso fanau" translates literally to "Have a blessed/happy birthday". Manuia - blessed; fiafia - happy.