NEWPORT — Harle Tinney said she was “relieved” after a state Supreme Court order on Monday denied the estate claim of a former plumber whom her mother-in-law adopted as a son, a ruling that keeps an art/antiquities collection intact at the family’s Belcourt Castle on fabled Bellevue Avenue.

It’s the third ruling by Rhode Island’s highest court in the matter, but described by Tinney and her lawyer yesterday as the final word after years of warring over the 60-room mansion that is also a public museum.

In 1974, Kevin Koellisch was hired to work on the estate’s plumbing. In 1990, he became Kevin Tinney, the adopted son at age 38 of Ruth E. Tinney, who was 84 at the time and lived in the mansion. Before the adoption, Kevin Tinney, according to court testimony, asked Ruth to marry him despite the age difference.

After Ruth Tinney’s death on Dec. 18, 1995, Kevin Tinney filed a lawsuit in 1997 against Harle (pronounced Harley) Tinney and her husband, Donald Tinney — Ruth’s biological son who died last year — alleging that the mansion was not being maintained by them and asked the court to allow him and a group of investors to buy it. Kevin Tinney’s name had been added to the property deed before Ruth’s death and he claimed a one-third interest in the property’s estimated value of $3.2 million. Harle and her husband contended that Kevin Tinney had no claim to the estate. The state Supreme Court in 2001 affirmed a 1999 Superior Court decision that denied Kevin Tinney’s claim to a share of the Belcourt Castle and ordered him to leave the property, where he had been living on the third floor for years, within one month. The court found he had played upon Ruth Tinney’s vulnerabilities to become adopted and pursue a stake in the estate.

Yesterday, Harle Tinney said that “we couldn’t see it at the time,” when Kevin Tinney took Ruth Tinney horseback riding and traveled with her.

“How could anyone stop her from being happy?” Harle Tinney said.0

In 2002, the Supreme Court upheld a Superior Court decision that Kevin Tinney did have some inheritance rights as an adopted child. When the matter went to Probate Court in Newport, however, the judge found the other Tinneys all had joint ownership of most items in Belcourt dating back to before Kevin Tinney was adopted, in effect leaving nothing to probate for him, according to Keith B. Kyle, the lawyer for Harle Tinney. An appeal to Superior Court failed. Kevin Tinney appealed to the state Supreme Court. This week the Supreme Court upheld the Superior Court ruling.

Kevin Tinney does get some items from the estate, which Harle Tinney said have an estimated value of $10,000 to $12,000.

The Tinney family acquired the property in the 1950s. Yesterday, with reporters gathered in high-backed chairs beneath an enormous chandelier in a Belcourt room, Harle Tinney said she wants to keep the castle a museum. She said British entrepreneur Peter de Savary decided not to buy the property and turn it into a club, a proposal that had been floated while the outcome of the court wrangling was less certain.

“Now that it is free of litigation, after nine years, we are really going forward to preserve it for the future,” she said. Some of that future may be brought about through the Royal Arts Foundation, which the Tinneys formed in the late 1960s. But she added: “We are going to need help from the community.”

The castle holds art and antiques from 33 countries. One room features walls that were disassembled from a room in a mansion outside Paris — a previous owner of Belcourt bought the French estate just so he could obtain those walls and ship them to Newport, according to Stephen Federico, director of museum services at Belcourt.