Technically ther is no such thing as next of kin under Scots law. Does your sister hold power of attorney? If not, she has no right to withhold this information and you should be told unless the care home has a specific instruction from your mother to the contrary. Even if there is a power of attorney, it has to be exercised in the best interests of the grantor and by withholding information as to her whereabouts from family, it would appear unlikely that this in your mother's best interests. You could report this as an abuse of the power of attorney to the Office of the Public Guardian in Scotland. I hope that helps. Please leave a positive rating so that I am credited for my time.