As I see it, those offices which have been clearly defined in the New Testament are all that we are
required. If leadership in the church determines that other positions are necessary to further the ministry of the Gospel, they are allowed under the jurisdiction of the elders and deacons (and only under their jurisdiction), just as Paul and the other apostles divided out responsibilities to those in the early church.
These positions are not required, nor are they to be ordained, and they don't necessarily need a title. If none of the elders can sing, and they want to appoint an individual to lead the singing to keep people on pitch and together, then they should feel free to do so.
I do not see any other offices outlined in the New Testament other than elder and deacon.
