Good stuff. I finished running a couple 10 year olds through Black Fang and had the same issue. One Rogue and one Wizard. I knew with no Cleric they would get chewed so I grabbed the pregen as a GM-PC. And yes, it is also handy if a younger sibling comes along and wants to play. I just hand them the sheet and tell them what dice to roll.
I didn't reduce any numbers and I ran the whole thing with just the three characters and they did fine. Mind you the rogue rolled a crit with Dragonsbane on Black Fang right off the bat which made that fight way easier.
The free Hero Lab works well for making chars but I found the kids were more into rolling physical dice and writing on their sheets.