Which branch of civil law would apply in a case in which one sister sues another over the possessions or property given to them after a family member dies?

The branch of civil law that would apply in this case is inheritance law, which falls under the broader category of estate law. This area addresses disputes related to the distribution of a deceased person's assets, including property and possessions. The case may involve issues of wills, trusts, or intestate succession, depending on whether the deceased left a will or not. Additionally, principles of property law may also come into play regarding ownership and transfer of assets.