Neil Wishinsky will run unopposed for the Board of Selectmen this spring, but there are four candidates vying for three seats on the School Committee, according to the town clerk’s office. Wishinksy, a member of the Advisory Committee, will be the only candidate on the April 30 ballot to fill the seat left vacant by Jesse Mermell, who stepped down in January. Two School Committee incumbents, Helen Charlupski and Susan Wolf Ditkoff, will be joined by David Pollak and Laurence Onie in the election campaign. The third seat on the ballot is being held by Henry Warren, who is not seeking reelection after 10 years on the board. There is also a five-way race for four library trustee positions, with incumbents Michael A. Burstein, Jennifer Rees, and Judith A. Vanderkay joined by challengers Puja P. Mehta and Magdalene M. Moran. Incumbent Roberta Winitzer is not seeking another term. There are also races for Town Meeting positions in several precincts. An updated list of the candidates on the ballot has been posted on the town clerk’s page at www.brooklinema.gov.