The Director may designate a central collection agency to obtain information for two or more agencies if the Director determines that the needs of such agencies for information will be adequately served by a single collection agency, and such sharing of data is not inconsistent with applicable law. In such cases the Director shall prescribe (with reference to the collection of information) the duties and functions of the collection agency so designated and of the agencies for which it is to act as agent (including reimbursement for costs). While the designation is in effect, an agency covered by the designation may not obtain for itself information for the agency which is the duty of the collection agency to obtain. The Director may modify the designation from time to time as circumstances require. The authority to designate under this section is subject to the provisions of section 3507(f) of this subchapter.