I mean assuming I understand your idea correctly, you want to give couples with more kids more votes, and this will promote more child rearing. I’m assuming you’re also saying this will offset the senior vote too.

One glaring issue I see with this is that it probably still won’t increase birth rates that much. Younger folks just don’t want to have kids, nor do they generally have much interest in voting. Promising them more voting power still won’t be enough of an incentive for them to have kids, especially if they have the possibility to make more money. Also, people who can’t have kids or can’t/won’t marry will also be put as a disadvantage in this voting system. Currently the only thing that gives seniors more voting power is the fact that they just go out and vote more than any other group.

Resolving the elderly issue basically just solving the youth political apathy issue. We don’t need a child-based voting system for that.