try going early in the morning to a local CC or park and see how the old folks go about their qigong or taiji routine.. can adapt some ideas. I think the main point is to take it slow and easy with the old folks.
what is the general health condition of the folks? are they on wheels, or general in the pink of health? or are they feeble just walking around? any forms of skeletal problem/ailment existing in them? and, what is the desired outcome of the exercise?
i understand you mean well, but you have to consider these questions before trying anything.
well some of the old folks have difficulty walking or standing so i think they might opt out of the exercise altogether. actually half of the grp are middle aged able bodied men while the other half are old folks. so i'm thinking of getting the right balance here.