This is the silliest au idea that has ever consumed me. ZoLuNa Timeskip Baby, Merry Bele (no surname, they couldn't agree).
Merry is like 17-18 months old, we are absolutely stretching the limits of the timeline to make her as old as possible. Basically, Zoro, Nami, and Luffy have been a throuple since the East Blue. If you want something a touch more detailed, their get together probably goes like this. Most of the crew are aware that Luffy and Zoro are together (mostly because the men all share a room) but it never crosses anyone's mind that Nami is also a member of this relationship, until she shows up post-ts with little Merry. I picture it escapes notice mostly because Zoro/Nami are fairly private with their affection to each other and the crew just doesn't register most Nami/Luffy affection as anything other than Luffy's normal behavior.
Nami probably finds out she's pregnant right before or right after Thriller Bark, so in addition to Zoro's injury they're also preoccupied with arguing about that when they go into Sabaody. Zoro and Nami both want to have the baby, but disagree on what to do after its born. Zoro thinks if they're going to have a kid, they should raise it. Nami thinks the only responsible option is to send it to Nojiko. Luffy is just absolutely petrified by the idea of being a father (for Ace reasons) and is pro abortion as soon as he learns that's an option. They don't reach a decision before being separated on Saboady, and then Luffy has to live through Marineford.
I think something about Ace's final words shift Luffy's thinking about the pregnancy, and before he goes to train with Rayleigh he asks Shakky if she could get a message to Nami. She says she'll do her best, and does manage to get a letter to Nami that just says he'll love the baby. Nami does actually send Merry to live with Nojiko about 6 months before she's set to reunite with the crew. It lasts exactly a month before Nami demands the Weather Wizards take her back to get her baby right now. Nojiko is very happy about this.
I also like the idea of Nami and Zoro being about to communicate via snail during the timeskip. Zoro only hearing about the pregnancy and their daughter through calls, feeling angry he can't be with his family but also feeling guilty because Luffy doesn't even have a snail. Zoro is the hover parent of these 3. He thinks she's so small. This also definitely adds to post timeskip anxiety that man will struggle with.
Merry probably spends most of Fishman Island with Luffy, hanging out with Shirahoshi. Then on Punk Hazard she's in The Worst Mood about Sanji in Nami's body. She won't meet Sabo in Dressrosa, but Zoro will awkwardly introduce himself as Luffy's partner when the two talk while Luffy's resting. I'm torn between her going to WCI or Wano, but I favor Merry going to Wano with Zoro. So, Zoro just gets to spend like a month wandering around his ancestral homeland with his daughter. Yasuie and him can bond over fatherhood.















