Day 2: It seems there's two ways that my mom can legally adopt Kenneth: through the Philippine court system (because she was a former Philippine national) and through conventional adoption. From my understanding, if my mom adopts Kenneth in the Philippines, he would legally be her adopted son, but he won't be able to move to the US because she doesn't meet the US requirements to petition him. In order to meet the US requirements, she would need to move to Philippines for 2 years, which is impossible, but even if it was, his age is the limiting factor. So initiating the adoption through the Philippine court system won't allow him to immigrate to the US -- which defeats the purpose of adopting him.
The second option is our only bet. This is where the Hague Convention falls in.
It appears that Kenneth would be eligible for adoption under the Hague Convention rules, but we won't know until I've spoken to an adoption agency (which is a requirement). I've contacted an approved agency listed in the Republic of the Philippines Inter-country Adoption Board. They advised me to call on Monday.