Some other clubs have been doing this for a few years, the more clubs like Barrow that catch up can only be a good thing. Well done to them

What happens if 5000 kids turn up with their parents to the next home game?

Bradford Northern were selling season tickets to under-18s for a fiver in the 1970s, so I could go see them every home game even though my family were not interested. As a result I've been a supporter (although from afar) ever since. Cheap tickets for the young worked in my case.

what would happen if 5000 kids turned up without their parents

They managed to get almost 2000 in for their game with West Wales. Good on them.

And to answer the previous point, I work at Alton Towers, try 20,000 kids on School Trips when most of the teachers are in the pub.