Hi Jackie, sorry we missed your post!
The current version of Little Reader (v2.0) does not have options for creating "child profiles" yet. This is something we've already included in the upcoming version 3, so do watch out for that one!
In the meantime, you can manually keep track of where each child is in the curriculum using the weekly lesson planners (if you bought a box set), or the built-in Progress Diary in LR.
Alternatively, if you have another computer, you may choose to install LR in that one (2nd installation) and you'll always use one computer with your older child, and the other computer with your younger child.
I hope this helps somehow!