Chellyroo - since my 5 and 7 year old boys are the subject of an overwhelming % of my photographs, I completely understand!
I have to agree with ImRaptor, the 50mm f/1.8 lens while sharp is very slow to focus. I sold it and upgraded to the 50mm f/1.4 almost solely for the faster autofocus. It was worth the time to save and upgrade.
Th 10-22 has reasonably fast USM focusing. Depending on how you are using it though, it can be challenging to let auto select the AF points due to the field of view. I have pretty good luck with it, but I cannot say I use it for portraits very often.
When I am shooting the kids in anything under f/5.6, I rarely let the camera select the AF points. I preselect one based on the compositions I usually prefer (usually on the traditional Rule of Third lines) and the camera orientation (landscape or portrait). If I am using a f/2.8 or lower with the narrow DoF, I can be prone to practice the SprayAndPray technique with the kids. It may add time in post to delete excessive shots, but with fast moving subjects in a low DoF it can help get the shot.