In 1985 Dinah Manoff (Leader of the Pack), Mary Beth Peil (The King and I) and Leilani Jones (Grind) could have been considered leads. For the men, Patrick Cassidy (Leader of the Pack), Ben Vereen (Grind), Timothy Nolen (Grind) and Daniel Jenkins (Big River) could have been in the leading category. However, it was determined that not enough of them were worthy of nomination so everyone got bumped to Featured.
OurTime - here's section from the rules that you're referring to. It's on page 6:
"There shall be no more than four nominees in each category; provided, that if there are at least seven eligible candidates for nomination in a Best Performance category, then there shall be five nominees in that category; and provided, further, that the Tony Awards Administration Committee shall also have the sole
discretion to reduce the number of nominees to fewer than four (or five), but, in no event, fewer than two, in a particular category for the current season or to delegate this discretion to the Nominating Committee."
http://www.tonyawards.com/en_US/about/Rules-2010-2011FINAL.pdf