BOSTON -- The Massachusetts Supreme Judicial Court is being asked to settle a lawsuit brought by the Daughters of St. Paul against the trustees of the Archdiocese of Boston's pension fund, which includes Cardinal Seán P. O'Malley.

In a lawsuit filed in December, the Daughters allege that the pension fund's 11 trustees have failed to give them a full accounting of their portion of the fund. They asked the Supreme Judicial Court to either order the trustees to give them those details or to rule that the nuns were never part of the plan and order the archdiocese to reimburse them for the contributions they made.

At issue are contributions the order made for their lay employees' pensions.

The Daughters and the archdiocese are scheduled to sit with a mediator on March 29.

"This is not an action by the nuns against the cardinal in his capacity as cardinal. They are suing the trustees, of which he is one," said Michael McLaughlin, the Boston-based attorney representing the sisters. "At first, we just thought there were some problems -- it's a big organization. As years went by, and very recently, it became clear that they didn't have the data."

The sisters claim in their lawsuit that the trustees did not keep separate records for the separate groups, which has complicated efforts to get a full accounting.

"The particular funds in question have been pooled with many, many, many other pools," McLaughlin said. "Our problem is seeing who gave what to that pool. ... We want the accounting or a determination that they were never part of it."

McLaughlin said that the Daughters have maintained their own records of their pension fund contributions.

The Archdiocese of Boston, however, said the sisters have been given the information they requested.

"We have provided employee-level detail, years of service, dollar amounts in the pool," said Carol Gustavson, the archdiocese's human resources, benefits and administration director. "We've given them all the information that we understood they were seeking."

She also said the archdiocese "would like to get this promptly resolved for their benefit as much as for the pension plan's benefit."

The archdiocese's communications secretary, Terrence Donilon, said the archdiocese has a good relationship with the Daughters of St. Paul and is confident the lawsuit can be resolved through mediation.

"We're happy to resolve this," he said. "We are trying to ensure that when they withdraw, that there's a plan that they are going to continue to provide for the well-being of the beneficiaries of the fund. We don't think that is a lot to ask."

Donilon said there are three issues that must be resolved: the value of the sisters' portion of the fund, the timeline for the spinoff, and the Daughters' request for the archdiocese to pay its legal fees.

Neither Donilon nor Gustavson would say what they believe the sisters' assets are worth. Gustavson said that is a calculation that will be resolved through mediation.

However, McLaughlin said the Daughters believe they are owed $1.37 million, based on the value of the assets in 2007.

The archdiocese invited the order to join the Pension Plan and Trust of the Roman Catholic Archdiocese of Boston in 1989, McLaughlin said. The plan includes retirement money for archdiocese employees and other Catholic organizations.

The sisters also say they have tried for more than five years to withdraw from the Boston archdiocese pension fund so they could set up a separate, self-run pension plan for their U.S. lay employees.

The lawsuit was first reported by the blog Boston Catholic Insider and was the subject of a story in the Boston Globe March 21.

The Daughters of St. Paul is an international order with about 60 members in Boston and 75 more around the country. Their provincial house is in Jamaica Plain, and they operate 15 bookstores from Dedham, south to Miami and as far west as Hawaii. The order produces their material locally but outsources its publishing.

The order has about 50 lay employees in the Boston area and 30 others around the country. The sisters also operate St. Thecla Retreat House in Billerica.