Probably not.  The key characteristic of a nonprofit organization, whether a charity, a trade association or any other type, is the “nondistribution constraint,” i.e. it may not distribute profits to its members or other insiders while the organization continues to function.  This is a characteristic of state law, not necessarily federal tax law.  (See Ready Reference Page: What Do We Mean When We Say ‘Nonprofit’?”) Therefore, the trade association cannot just give rebates to its members based on the dividends it receives from its subsidiary insurance company.

The association already has a redistribution plan in effect, however, by allowing the association’s members to earn a marketing fee from marketing the subsidiary’s products to their members.  It isn’t clear from what you say whether this generates unrelated business taxable income for the association’s members (especially from marketing to the general public), but it redistributes what would have been profit paid as a dividend to the association to a marketing fee paid directly to the association’s members.  Since the association controls the subsidiary, the association could cause the subsidiary to increase the marketing fee and reduce the dividend and get closer to the objective you hope to achieve. 

The association could also reduce its membership dues and operate off the dividend income to reduce the members’ cost of doing business and move closer to your goals.

There may be other ways to get closer to what you want, but don’t do any of this without good professional advice.  You haven’t given me enough information to be sure what might work without some adverse tax consequences or how any plan would relate to the amount of the re-distribution you may want among your various members.