1. Personally I feel like trends over time are most of the time best scene as line graphs. This allows people looking at the graphs to clearly interpret positive and negative difference month to month.
2. If I was given the opion I would likely separate employee, spouses, and children into three diffent graphs so that I could use line graphs unless there was a reason to compare memberships of employees over time vs spouse/ children.
3. I would maintain my graph choice if comparing Eastern and Northern. I would actually argue that I may not need to split up employee, spouses and children until we are comparing Eastern and Northern.