Yeah Offspring has been featured in the book. Plas is trying to reconnect with him after being stuck in that egg form for years as shown in Metal. Offspring was pissed that Plas had seemingly abandoned him and his mom. So they went through the father son reconciliation stuff. Offspring has suited up in costume and helped the team but they may still focus on the main four members going forward. Though Offspring and Phantom Girl having a romantic relationship would be cool. Plas playing the worried father and all.