The SplitView component doesn't handle the case where new item are reparented to it. For example by using the function Component.createObject() and specifing the SplitView as parent. Here's another example:

 
SplitView
{
  id: splitView
}

Item
{
  id: item
  Component.onCompleted: item.parent = splitView
}

Looking at the source code of the SplitView we see that the components and children are handled only in the init() function that is called only on Component.onCompleted.