The two-day tournament, which kicks off after lunch today at the Happy Valley Field in Takuvaine, will now feature the six clubs from Rarotonga.
After Atiu pulled out, CIRU had to drop Mitiaro to make the pools even – three teams in each pool.
Pool A will have the reigning champions Avatiu Eels, Arorangi Cowboys and Titikaveka Bulls.
Tupapa Panthers is the top seed in Pool B which also includes Takuvaine Reds and Ngatangiia/Matavera Dragons.
The Under-16 competition will still feature Eels, Cowboys, Panthers and Dragons.
The Steinlager Sevens tournaments will be used by the national coach Vase Samania to help him select the Cook Islands team for the Oceania Sevens Championship to be held later in the year.
It will also assist the clubs in working out their combination ahead of the weekly club competition which starts later this month.
CIRU chief executive officer Ben Koteka said the tournament will also be used to help select a U15 and U18 Cook Islands Sevens schools teams to attend the U15 Condor Sevens and U18 World Schools Sevens to be held in New Zealand in December this year.
12.55pm: Opening Prayer in front of the Admin Tent (U16 - Eels and Cowboys are to please line up in-front of the Admin Tent), 1pm U16 Eels-Cowboys, 1.17pm U16 Panthers-Dragons, 1.34pm Eels-Cowboys, 1.51pm Panthers-TKV Reds, 2.08pm U16 Eels-Panthers, 2.25pm U16 Cowboys-Dragons, 3.16pm Eels-Bulls, 3.33pm Panthers-Dragons, 3.50pm U16 Cowboys-Panthers, 4.07pm U16 Eels-Dragons, 4.24pm Bulls-Cowboys, 4.41pm TKV Reds-Dragons, Closing Prayer, Team Managers Meeting at the Admin Tent.