Message Groups tweak is developed to organize conversations in iOS Messages app. It provides an ability to divide your conversations into categories just like your wish. The possibilities are endless.
By default Message Groups creates list of default groups for you, by name they are All, All Groups, Favorites and Unknown. This provides a flexibility for you to switch between different list of conversations easily.
Also Message Groups has an ability to set ‘Password’ protection (requires TouchID) to newly creating groups. This provides excellent flexibility to you protecting certain conversations being visible to others.