I have a feeling Mysterious 6 is a more powerful organization than the DeLuca Family too. Because they were able to keep Cordia from finding Luna for several months (enough for Cordia to go on warpath with all the families, risking breaking alliance with basically everyone). Not only that, but they also managed to nab Lucan as well. Just comes to show the Mysterious 6 is likely more powerful and has more resource at their disposal than DeLucas.
I'm just guessing here, but I think all the allies DeLucas have are more of smaller or medium sized families. The rest of the Big 5 Crime Families (which of course excludes the DeLucas), I think may just dislike the DeLuca Family in general (to varying degrees. Perhaps these other Dons are jealous of the DeLucas notoriety & fame, or perhaps there is greed for territories coming into play. Or even some hidden vendetta between some of these familes history).
With Pacifitoris, they seem to serve as people giving out the rules of conduct for these families, but I do wonder if they would even be effective if all the families are plunged into war.
I mean for example, if all 4 major Crime families decide to put any differences they have aside and ally with each other to attack the DeLucas, would the Pacifitori organization even be able to do anything about it?
They would either need some major firepower or tremendous attack force to keep any Families who gets out of control back in line.
That being said, if the organization existed for a long time, i.e. even back when child Luna was kidnapped by the Mysterious 6, were they even effective when Cordia was on rampage warpath against the other families desperately searching for Luna? Hmmmm