No, absolutely not. If the older child ‘picked’ a name that we were already considering, I might let them think they had chosen the name. But I wouldn’t actually do it. They’ll have their own chance to have children and name them when they’re grown up. I would let them name a pet, provided it wasn’t something I would be embarrassed to call the pet, but not a sibling.
I don’t think I would even risk the ‘pick from a list of preapproved names’ trick, unless I was absolutely certain that my feelings on the names were equal and I honestly didn’t mind which one. Otherwise the older child might pick something off the list, and then you change your mind and know that another name from the list is ‘the one’. Then the sibling will just feel betrayed and upset when it turns out they can’t pick after all.
I would involve the older sibling in discussions if they were old enough to have an opinion, but ultimately, no, it’s not up to them. Plus, from my experience with young children picking names, the majority of times they will choose the name of a character they like, from a film or a book or a TV programme. That’s very hit and miss. [name_m]Thomas[/name_m] after a [name_m]Power[/name_m] [name_m]Ranger[/name_m] is fine, [name_m]Simba[/name_m] from The [name_m]Lion[/name_m] [name_m]King[/name_m] is not.