The affiliation would give the smaller network access to a shared electronic medical record platform and joint purchasing, among other benefits, it says. File photo by Glenn Russell/VTDigger Dartmouth Health network’s already large influence in the Vermont health care market is likely to grow next year with the addition of Southwestern Vermont Health Care. The board of trustees of the smaller network, which includes a hospital in Bennington and medical clinics in Manchester, Pownal and Wilmington, approved an “integration agreement” in late November that would allow it to become a member of Dartmouth Health, according to an email to staff from SVHC’s president and chief operating officer first reported by…