This seems to be the most popular breastfeeding group on Facebook in the Philippines: https://www.facebook.com/BreastfeedingPhilippines/ Though, I don't know if they focus exclusively on extended feeding. I know that L.A.T.C.H. has a big community here! They're a a non-profit that would more than likely have information that you're looking for. Check them out here: https://www.facebook.com/theperfectLATCH/
Yes Breastfeeding Pinay is the most active breastfeeding group. They tackle everything even extended breastfeeding. They have the most numbers of followers or members too.
mori mommy at facebook check that out