Is it legal to carry property insurance on someone else's property?

Insurance for someone else's propertyYes, You can legally Insure the property of another person. So Long as you have authorization to do so and the owner is benefited, or an other insurable interest in that property exists.

There are many situations where a third party may need to obtain property insurance such as, Estate Executors, Court Appointed Trustees, Dependents, Bailees, Tenants, Persons holding POA, or living wills, etc..

You can not insure the property of another when no insurable interest exists. It would be unlawful to insure the property or life of another where the intent is to gain unduly from another persons loss.