In its 2012 decision In Re Estate of Kazmark, the Washington Court of Appeals resolved the question whether Earle Sr. was bound by agreement with his predeceased spouse Barbara, to keep his Will in place that benefited her family as well as his.
Barbara's son Shane first had to rebut Earle Jr.'s assertion that Earle Sr. and Barbara's Community Property Agreement superseded their Wills and any agreement under which the Wills were made. The Community Property Agreement did override the Wills in a sense. It was used upon Barbara's death to transfer the whole estate to Earle Sr. without the necessity of probating or otherwise using Barbara's Will at all. But the Court didn't have much trouble refusing Earle Jr. on this one. The Community Property Agreement was entirely consistent with the Wills, accomplishing more easily what Barbara's Will would have done upon her death. Because it only supported the work of the 2005 Wills, the Community Property didn't supersede or otherwise negate them or any agreement they represented.
Shane's other main challenge was overcome the statute of frauds. He argued that, despite that statute requiring agreements affecting real estate to be in writing, there was part performance of this contract, thus escaping the rule. The statute of frauds would apply, for instance, where X agreed only orally to sell property to Y, and likely leave Y without a remedy. However, if Y had made payments to X, built a house on the property, and moved into it, he could establish the oral agreement as valid. In the Kazmark case, the court accepted part performance of a less obvious sort. It found that, once Barbara and Earle Sr. had made their oral agreement, her act of then dying with the agreement in place, was part performance. So Shane succeeded on both primary issues, the oral agreement was acknowledged by the Court, and Earle Jr. had to share the estate with stepbrother Shane.
Shane's success came only after a trial and and an appeal. Had the Wills said that they were mutually binding, or the opposite, there might not have been much of a dispute, at least on these issues. But it's easy to find fault in retrospect. And the Court's opinion reveals that the estate was about $2 million and that Earle Sr. and Barbara each had other children from whom they were estranged. so chances are that in this testy mix other issues would have seemed primary and compelling had these not arisen.