Just for another point of reference, all youth leaders are (generally) welcome at our troop’s
the PLC, although the SPL and SM set up a list of the “required” attendees, based on what topics will be discussed and what support is needed. I generally attend, either as a second adult or in the SM’s role if he isn’t able to attend. We have always had at least two adult leaders present. Our role is generally to ask questions, when necessary, like “What are you going to need to execute that?” if it seems like something isn’t thought through enough, or “How many passenger seats am I soliciting from the adults?” so we can get the ball rolling on drivers. Usually, we don’t have to ask the same question at too many meetings before one or another of the scouts starts asking it without prompting.
Generally, the SPL/SM also invites any adult advisers for positions that may need adult support. For example, if the Outdoor Ethics Guide is planning a OE event, his adviser will be added to the invitee list so they are aware of what’s coming up and what support the youth leader might need, and don’t have to wait on the scribe and SM getting the word out.
Our SPLs have been pretty firm about keeping out the peanut gallery (youth and adult). I suspect it’s because of a desire to minimize distractions, but I couldn’t say for sure, not having asked. I know from experience it’s hard enough to keep any meeting (not just PLC) on track just with everyone who needs to be there. Adding more people generally seems to lead to more questions. Not necessarily a bad issue overall (more thinking about a topic often leads to better long-term outcomes), but one that can make it difficult for the meeting to complete its agenda.
One thing I would like to see more of is our assistant patrol leaders attending the PLC. Whether or not the patrol leader can attend, having the APL there means that there’s continuity of knowledge if the PL isn’t able to attend a troop/patrol meeting to communicate the plan to everyone and/or manage its execution.