This is a great question and one which I'm sure every parent will relate to. There are a couple of aspects which immediately spring to mind. The first is how we define mindfulness. Because although during meditation our attention is focused on just one thing, that is purely in the best interests of training the mind. When we apply mindfulness in everyday life, it is about moment-to-moment awareness. It's about moving from one thing to the next, at whatever speed is required of us at the time. This means we can apply this approach to every situation.
At first, this is not easy—especially if there are multiple things to focus on. It's a bit like how learning to ride a bike on a flat surface with no traffic is quite easy. But then we add cars, bumps on the road, traffic signals, billboards and all these other things. It can almost sound like too much. But if we just get on the bike each day, over time we become more proficient at processing all this information and staying with the task at hand while still being aware of everything else that is going on. More than that, we remain ready to engage or respond to any of those things when appropriate.
If I apply that to life at home, one moment I'm eating my toast and aware of the taste of honey, maybe the texture of the bread. The next, I'm aware of the pain of my shins being bashed by the baby car our son runs around in. Next, my awareness moves to the clock to see if I am late for work, and then back to the honey... and on it goes. If we can learn to move, consciously, from one moment to the next in this way, then it's quite possible to feel at ease, even in the midst of all the madness.
But the most important aspect of all is compassion. Mindfulness is about more than awareness, it is also about the willingness and desire to see others be happy. Along the way, we sometimes find ourselves leaning more towards compassion and sometimes more towards awareness, but both are vital supports for our practice. So, bottom line, when it all feels like too much and as though you simply can't get your head around the idea of awareness, lean on the support of compassion. Simply focus on the love you feel for your children, the feeling you experience when you are not caught up in lots of thought. Sometimes this is enough to bring us right back to where we want to be: here and now with those that we love.
Warm wishes, Andy