The family tree for these guys is always very hard to work on when there's very little information. Anyway, TTPI was organically South Seas Mandate, which is why she has the parentage she does. Since the UN sort of moved it from Japan's hands to America, I wanted to keep them the same. I had a hard time figuring out when I wanted the former TTPI guys to be born, but I eventually decided on doing it when the districts were made, which included NMI, and had Micronesia born when the country was created, since the states made the country, with Pohnpei as the parent, since the Micronesian capital is in that state.
OH THIS IS SO COOL!!!!! I am admiring your family tree making skills with such awe, I tried using that website once and it hurt my brain lol I suuuck at family trees :P But this IS so awesome. Yap, Chuuk, Mariana, Palau, Marshall, and Pohnpei sharing a birthday is very cute, ACTUALLY I ended up drawing them all together just because the idea of them all hanging out made me smile. Though my FSM is a system, so this is based in your world I suppose!
(Side note: I do wonder where Nauru would be on this: Considering it was incorporated into the Marshall Islands after Germany annexed it but was later captured by the Australians-- I've always considered him and Marshall to be brothers because of that, But I also play very loose with my family tree, so I'm curious to see how you'd interpret it!)