The committee may recommend, and pursuant thereto, the Secretary may approve, the reapportionment of members among districts, and the reestablishment of districts within the production area. In recommending any such changes, the committee shall give consideration to:

(a) Shifts in onion acreage within the districts and within the production area during recent years;

(b) The importance of new production in its relation to existing districts;

(c) The equitable relationship of committee membership and districts;

(d) Economies to result for producers in promoting efficient administration due to redistricting or reapportionment of members within districts; and

(e) Other relevant factors. No change in districting or in apportionment of members within districts may become effective less than 30 days prior to the date on which terms of office begin each year and no recommendations for such redistricting or reapportionment may be made less than six months prior to such date.