My father's hiding his wealth from us for his 2nd family

My mom left my dad in 1991/92 because my dad was physically hurting us as means of discipline. They're legally married. My dad didn't support us in any financial way nor didn't contact us after my mom tried getting support. My mom's family supported us with education and everyday needs 'til we're able to stand on our own. He now has a 2nd family with 2 kids. He suddenly appears out of the blue and gives us a house and lot. We've learned that he's now here in Metro Manila, living the life and hiding from us because he's afraid of our legal rights, if there's any, to his wealth. What can we/my mom do so we could get what is rightfully ours? I have a contact from a relative, father side and is willing to provide information. He told me that me and my family(mom and 2 siblings) are being mocked by them and papa's hiding roughly a hundred million. We're thinking of surprising him as they're thinking of transferring his wealth to his 2nd wife and other relatives. Not to mention all of my dad's and his 2nd wife's relatives are protecting them from us. Please help us. I don't know where to start and is very willing to be in touch with a lawyer for what can be done.