A nonconforming building or structure may not be enlarged, extended, increased in height, width or depth; moved or relocated; or modified in such a way so as to increase habitable or usable space, number of dwelling units or number of bedrooms, unless it is changed to conform to the requirements of this chapter except that an existing use (principal or accessory) may be enlarged, extended or added to, provided that:
(a) The proposed use and all existing use(s) is/are permitted principal or accessory use(s).
(b) The enlargement, extension or addition conforms to all requirements of this chapter and will not result in the creation of any nonconformity related to the lot and the aggregate of all structures or building.