Great Question
The adult members of the order of the arrow are advisors to the youth leadership, whether they like it or not. Along with donating a lifetime of cheerful service, they are more or less expected to impart their knowledge and wisdom upon younger generations. A perfect example is the elders of any indian nation.
I would Encourage each adult to relay his/ her imput on any subject, make suggestions and generally interact with the youth run meeting. Imput they add could prove to be invaluable. Other than that, I would encourage you to give them something to work on to