Wairoa club Tapuae, the 2019 senior one competition champions, will remain in that grade this year.
Pirates combined with GMC to field a team in the premier grade last season but they are entering just as Pirates this year.
Richard “Tiny” White was Poverty Bay's first All Black and played 23 tests.
The lock was one of the best forwards for the All Blacks in the 1950s and stood out in the 1956 series against the Springboks.
OBM hosted the opening round of Poverty Bay club rugby last season and HSOB fullback Andrew Tauatevalu was awarded the Tiny White Medal for player of the day.
In 2019, the host club lost their opening-round clash with YMP, 2018 champions Waikohu were tipped over by HSOB, and Ngatapa were too good for Pirates-GMC.
OBM went on to beat YMP 65-5 in last year's final.