Electricity usage for 2 kids really doesn't increase the amount a whole lot. We all watch the same TV when its on, when using the oven we're using the same electric as cooking for 1 person that you'd use for cooking for 6 etc. When using the dishwasher, you use the same saucepans and pans to cook for 2 as you do for 4, you just have a couple of extra plates besides.
The biggest difference is largely going to be the more frequent use of the washing machine but on an eco run it uses only pennies anyway. Most of the electric appliances that the kids use are all low-powered, mobile phones, tablets and the like. My biggest background drain is my fridge and my wifi/router plus a few smart devices (around 100w) - there's no reducing that.