A Hundred Ways to Show Affection on a Parenting Variety Show [Crossover]

Oikawa is a world-famous starting setter for Argentina's Japanese-descended men's national volleyball team. The first thing he does after returning home is join a celebrity parenting variety show. Countless fans and supporters burst into tears. So Oikawa really did get married young? Once filming begins, Oikawa realizes the show is nothing like he imagined. Wasn't it supposed to promote different sports? Wasn't it supposed to give athletes a chance to get along? Wasn't it just a place for the dads to share parenting tips? Why does everyone keep talking about their significant other? Oikawa gradually understands. This is just a different kind of dating show. How could the great Oikawa ever lose at showing off his love? Little Tobio, out for a morning run in Rome, couldn't help shivering. It's summer, so why did it suddenly get so cold? Note: 1. I've added a little ABO element, just to make having children more plausible. 2. The main pairing is Oikawa and Kageyama. There are side pairings, including but not limited to Gojo and Fushiguro, and Yukimura and Fuji. My preferences take priority. 3. The children are the fruits of love. 4. The children take the surname of the parent who gives birth. 5. Please don't offer unsolicited writing advice, but friendly discussion is welcome. Theme: A loving couple, and a child who's a wonderful surprise.