Child support

My husband has children from his previous relationship. From the time we got married, we send money monthly. Yet the kids never appreciated their father's support and kept telling their relatives that they don't get support from their father. We, me and my husband just shrugged it off because we both knew that it is not true and we have proof of remittances as well. But just this year, we found out that the kids have been lying all along. They were never enrolled to private schools, which my husband paid for tuition fees, books, uniforms and other necessities. I would like to know since we, me and my husband, have our own kids growing too.. how would be the set up for the support. We have tried our best to talk to the mother/my husband's former partner but never cooperated.