I think, though I'm not sure, that the Israeli Arab suicide bomber was an Israeli through naturalization, one of his parents maaried an Israeli Arab. (I thought I mentioned that in the last thread)
Are you sure there are 3 in custody accused of planning suicide attacks? I know there are a few accused of various levels of complicity, such as a taxi driver who knowingly accepted a suicide bomber as a passenger.
However, it's not just Israeli Arabs who have aided the Palestinian terrorists. An Israeli Christian, an immigrant from Russia, is also awaiting trial for helping plan suicide bombings, and two members of the IDF, who are also settlers, are in custody awaiting trial for selling arms and ammunition to Palestinian terrorists.