A number of European nations, Japan and Singapore have shown that financial incentives like this do NOT work.
When you have an anti-natalist view, telling people how hard it is to raise children, how expensive it is, that the planet is dying and too many children are akin to murder of both them and Mommy Earth ... paying the people who grew up in that “environment” to have another baby only leads to those who wanted two children having the second sooner than planned.
You have to truly change the culture to pro-life and respect for families to turn it around. Hungary is managing this.
Georgia has, as well, with the head of their national church personally becoming the Godfather of all third and later children. So they’ve managed to raise the rate of third and fourth born children even as the number of illegitimate children has declined. This is an example of how religious cultural institutions CAN turn around birth rate declines while no state has achieved it without totalitarian coercion (looking at you Romania).
Maybe if Tochinoshin were to be godfather. .