Los Angeles, Oct 4 : Singer Joe Jonas and actress Sophie Turner will start four days of mediation on Wednesday. The former couple, who separated last month after four years of marriage, are to meet to try and agree on the terms of their divorce, including custody of their daughters Willa, three, and 14-month-old Delphine, with the "Game of Thrones" actress' lawyer pledging to go "full hog" to resolve the issues, reports aceshowbiz.com. Judge Katherine Polk Failla, in a hearing held on Tuesday set a date of January 2 for a trial for deciding custody but she said she had "high hopes for the mediation." The 27-year-old actress' lawyer, Stephen Cullen, had told the court there had been "some difficulty" between the two sides in regards to scheduling a trial but felt it would likely last no more than two-and-a-half days as it only needed to cover a "very narrow" range of issues such as where the children's habitual residence will be. He insisted it was "essential" for the trial to carry out this year because both parties are "very young litigants'" with "extremely young children." Asked if he wanted to set a trial date given mediation was due to take place, the lawyer said he wanted it to run "parallel." According to DailyMail.com, he added, "We are starting mediation tomorrow and are going full hog to do everything we possibly can to resolve this matter." He said the interim order previously signed that agreed the children would stay in New York for the time being would be "addressed head-on" during this week's discussions, and argued the "Sucker" singer's request for 50/50 custody would "evaporate" many of 34-year-old Joe's defenses in the case. Meanwhile, Joe's lawyer, Richard Min, insisted his client couldn't be available for a trial until the Jonas Brothers' current tour takes a break on December 9, and admitted he was neither "optimistic or pessimistic about mediation." He added, "Four full days of mediation is a lot of time for these parties to sit in a room together and iron out their differences." Unlike Sophie's lawyer, Richard believed a trial will take at least five days and would have a "significant" number of witnesses, not just the former couple. He said, "These are two individuals who have a lot of family, friends, social contacts and business relationships that factor into their decision making and their discussions." But Stephen argued he wanted to "'vehemently disagree with the need for a raft of depositions" and told the court both parties had an "obligation to bring down the mercury" and resolve the case in the quickest and least expensive way possible. Neither Sophie nor Joe were in court for the hearing, but the "Dark Phoenix" actress - who currently has care of the girls - joined the hearing via video call. /IANS