I use British Airways household accounts - this allows any child under 18 to earn both status and miles on oneworld flights (hence why my 2 year old was BA Gold/Oneworld Emerald only shortly after their birthday). Note, this is only valid for child tickets or infant in seat where you are paying a real amount of money rather than the 10%+ taxes, i.e. not lap infants (though BA will let you set up an account from birth airline websites wouldn't let your lap infant enter a FFP). I'm not sure if your child can have a higher status than you, but there is no obvious reason why not. Good news is that, even if the fare costs less, they seem to earn the same status & Avios & status-linked Avios as the parent's ticket.

Further details here:
https://www.headforpoints.com/2023/0...accounts-work/
https://www.headforpoints.com/2024/0...ehold-account/

Note: To get real status you need to take 2 to 4 BA flights (or BA codeshares) per tier point earning year, so unless you travel to Europe, you may be stuck with the kid just earning base points, but better than nothing.