Officials from several trade groups are mulling over their responses to a recently finalized rule compelling the Federal Home Loan Banks to register with the Securities and Exchange Commission. Generally, officials say the plan involves too many uncertainties. “It does seem as though our choices are limited,” said William Zuppe, chairman of America’s Community Bankers, following a conference on FHLBank issues last week. “One is to lie down, another is to legislate, and a third is