In Carnes v. Carnes, Ky., 704 S.W.2d 207 (1986), the trial court awarded joint custody to the mother and father of two infant children. The mother was granted the actual physical custody of the children for the greater part of the time, but when she encountered personal difficulties, she allowed the children to live with their father. After the children resided with their father for approximately six months, he moved the trial court to modify the joint custody decree and grant him sole custody. Pursuant to KRS 403.340(2)(b), the trial court granted sole custody to the father based on a finding that the children had become integrated into his family unit with the consent and permission of the mother. Although the court of appeals reversed the case, the supreme court reversed the court of appeals and upheld the trial court's modification of joint custody.