Iris (the Second) and Jai West
Who They Are: The twins of Wally West (*1) and Linda Park, both had superpowers. Iris briefly became Impulse and it left a question of what the future held for the then powerless Jai.
The Problem: Besides the crowd saying kids age Wally, "ruin" him and it's weird that Barry doesn't currently have kids? Their advance aging felt like a tired cliche to make them older without aging their parents. Now they could make them younger than Jon and still age naturally.
Should They Return?: I think they have a lot of untapped potential that could be done better this time around. Having them return will make the drama with Wally and Linda feel like it has a huge pay off.
Who They Are: The son of General Zod and Ursa who became the adopted son of Lois Lane and Clark Kent. For a while he was a hero known as Nightwing.
The Problem: The whole advanced age plot which brought us the horribly awkward Nightwing/Flamebird storyline. Basically Chris turned into a teen although he was still a kid and was part of a reincarnation thing with Kara's best friend Thara Ak-Var. It was extremely awkward and weird. If Chris did return without this baggage it's uncertain if DC would let him be the Kents adopted son again.
Should They Return?: Only if DC doesn't repeat the same mistakes and if they don't reduce him to a villain for Jon. Ideally I'd love for him to be Jon's adopted brother. Given his birth parents and their desire for fellow kids like themselves the Krypton connection could be an incredible dynamic. At the moment I don't think DC wants to have Chris return which is a shame. Chris kept a core idea of Superman alive. The concept of an adopted child belonging in a setting that is alien to them because their accepted and loved.
Who They Are: The daughter of Roy Harper and Jade Nguyen. In Kingdom Come she was known as Red Hood.
The Problem: I don't know what DC thought the problem was when she died. In current canon Chershire is insane so I don't know how Roy could have gotten together with her. Seriously she was written so unstable and acted like she was going to attack him. Sexually. Then she got all weepy because he had someone he loved. It mood whiplash for me. Maybe if the relationship was once again written as a fling with her maybe during his drunk party phrase? I just don't see Roy wanting to be around Jade when they were around each other in the relaunch.
Should They Return?: I always liked Lian and having her around would help develop Roy into a more mature character. Not sure how DC feels about her.
Who They Are: A girl Booster Gold saved and Michelle demanded they keep. For some vague reason.
The Problem: I had many problems with Rani chief among them was never knowing what her purpose was. She was smart like Rip but what's the point in having a genius kid when Rip already was/is going to be that a genius kid that saves all of creation? She was more of Michelle's kid since she wanted to keep her and her brother was always away. Rip didn't seem to grow up with her and Rani had people looking for her. So it didn't seem like Rani was supposed to be with the Carters.
Should They Return?: I'd say no unless DC could give her some role. She was never adopted by Booster so either return her to whoever was looking for her, have her be Michelle's kid and/or show who she is in the future.
Who They Are: The daughter of Circe and Ares.
The Problem: I really don't see any unless DC gave her an unneeded heel turn. Lyta was sweet and didn't want anything to do with hurting others. She was taken in by the Amazons after Circe was captured before Ares kidnapped her.
Should They Return?: I saw an awesome idea someone had to have Lyta be the new Wonder Girl of Damian's generation. I adore this concept. With the power she's sure to have the magic could set her apart more from the other Wonders.
Who They Are: Son of Donna Troy and Terry Long. In an alternate universe he became a villain known as Lord Chaos.
The Problem: The Lord Chaos stuff happened because he was born with too much power and aged himself into adulthood. But that was solved. I think the main problem, besides no one knowing what to do with him, was the fact Robert was related to Terry. And well, Terry wasn't popular and no one wants to think of him spawning with any of the female heroes.
Should They Return?: Unless Terry was completely redone or Robert has a different father I can't see him returning. I do like the idea of Amazons having male children but I don't think the idea was ever done justice.
Arthur Curry Junior
Who They Are: Son of King Arthur Curry and Queen Mera. Known as Aquababy, was killed during a conflict with Black Manta.
The Problem: Unknown if he ever existed now and I'm unsure if DC would want to undo his death if he did.
Should They Return?: It would be cool and he's be old enough to effect the plot more. I just don't think DC is interested in that. He has been saved in animated adaptions.
There are others of course but I'm not sure if their even be considered by DC. Lena Luther the second for example was Lex's daughter named after his then foster sister who died. With Lex having a birth sister that hates him I'm not sure if he'd have a kid named after her.
*1 The red headed Wally West.