The other person who seems to have heard through family lore that Margaret Hunter was full-blood Cherokee is registered with Ancestry as dwth631 - it's too bad he/she hasn't replied to your request for information about her native american heritage before now.
However, I can confirm that the digitized original baptismal registration for Margaret Hunter, wife of George Anderson Lunan, clearly shows that she was born in Godmanchester Township, Province of Quebec on September 14, 1864 and was adopted by George Hunter and his wife, Isabella Hunter (maiden surname Cockburn). There is no possibility that Margaret (Maggie) Hunter was full-blood native american (Cherokee) based on the birthplace information contained in her 1868 baptismal record.