NSPs officially came about August , 1989. Same time they did away with Skill Awards, time requirements for T-2-1 ranks,, no more Scouts on BORs, etc. But some troops apparently did it like your troop prior to that, and it influenced National. Although I bet how the LDS troops do it, i.e. 11 year old Scout Patrol, caused national to create NSPs. I know my troop tried it in 1986 at the request of the council, and it was a complete failure. Every time I've seen NSPs in action, it is either a failure, or turns into Webelos 3. But that has been my experience.
Some ideas.