I have never check Y award values, but from memory it is 48K points one-way PER-LAX as the cheapest option, so you need 192K points for 2 Y round-trip awards (or perhaps leave the son in the US as a one-way award?). So your first problem is determining whether you have enough points for what you want (and if not, how to get them or to change the award to something that you can afford). The cost of the award goes up with using different airlines such as CX, and routing via UK costs substantially more but might be a good option (better for easter US than for LAX).