A judge in a Barcelona court ruled in favour of the appeal Sanchez Vicario lodged to overturn a previous court decision to close the case.
The four-time Grand Slam winner's mother has denied that the family mishandled her daughter's winnings.
In addition to her father Emilio and brother Javier, the court said lawyer Bonaventura Castellanos Matarrodona and economist Francisco de Paula Oro Clot will also have to testify before a judge.
In 2012, Sanchez Vicario published a book in which she blamed her family for losing 45 million euros ($60 million) in career earnings through mismanagement.
Speaking in defence of the rest of the family, Sanchez Vicario's mother, Marisa Vicario Rubio, said when the book came out that "we never took advantage of Arantxa and under no circumstances is she broke."
Sanchez Vicario won the French Open three times, the U.S. Open once, and made the final of Wimbledon and the Australian Open. She added 10 more doubles or mixed doubles titles from Grand Slams. She also helped Spain win the Fed Cup five times, and was the first Spanish woman elected to the International Tennis Hall of Fame in 2007.