No discussion really necessary.
Cub Scout camping is family camping.
Boys Scouts, and older is not.
From the BSA Guide To Safe Scouting -
All Scouts registered in Boy Scout troops are eligible to participate in troop or patrol overnight campouts, camporees, and resident camps.
Boy Scouts and Varsity Scouts 12 through 17 are eligible to participate in national jamborees. Boy Scouts and Varsity Scouts 13 through 17 are also eligible to participate in world jamborees and high-adventure programs.
If a well-meaning leader brings along a child who does not meet these age guidelines, disservice is done to the unit because of distractions often caused by younger children. A disservice is also done to the child, who is not trained to participate in such an activity and who, as a nonmember of the group, may be ignored by the older campers.
So, unless your "long time Boy Scout leaders" can come up with something, in writing, from BSA, bringing siblings along on Boy Scout trips is not recommended.