Hi Paul,
There is no such for Marketo as a Parent campaign and a child campaign. There are only campaigns 
From my experience, and based on how SFDC works, I'd rather sync Marketo program with Child campaigns or push leads to child campaigns. Then, in SFDC, you let SFDC compile the hierarchy total.
If you push Marketo leads to the parent campaigns and not to the child ones, then the child campaigns become useless.
If you push Marketo leads to both the parent and the child, they will be counted twice AFAIK in SFDC hierarchy computation.
Finally, in the program analyzer, instead of looking into individual programs, you can group them by channel.
-Greg