I would look at another option. Most international tickets give 25% to 33% off for children aged 2-11. So all else equal, you want to use the miles for the adult tickets and you want to pay for the children's tickets since they would be cheaper. The savings by paying for the children might not be worth it if you consider the value of the miles that might be used by the adults. It is a judgment call.

I assume that two people want to travel together (most likely one adult and one child). It is playing a bit of Russian roulette to book the award tickets now but keep waiting for a better deal to come along for the paid tickets. You can do that, but if a deal never comes along, the paid tickets for the flights to match the frequent flyer tickets might sell out for the cheapest fares and you end up paying more for them. Or you redeposit your miles for a fee and start all over again.

If it were me, I would book award tickets and then before they are issued (you usually have a few days), find the best deal you can on paid tickets to match the frequent flyer tickets. That way you are certain to be on the same flights.