Introduction:
Family Law is an important subject in the UPSC Law Optional exam. It deals with legal issues related to families, marriage, divorce, adoption, maintenance, and inheritance. Aspirants should have a thorough understanding of the subject to score well in this section. Here are some recommended books for Family Law in the UPSC Law Optional exam:

1. Family Law by Paras Diwan:
- This book provides a comprehensive analysis of various aspects of family law.
- It covers topics such as marriage, divorce, adoption, maintenance, and inheritance.
- The book also includes case laws and landmark judgments to help candidates understand the practical application of family law.

2. Modern Hindu Law by Paras Diwan:
- This book focuses on Hindu Law, which is an important aspect of Family Law in India.
- It covers topics such as marriage, divorce, adoption, maintenance, and succession under Hindu Law.
- The book also includes relevant provisions of the Hindu Marriage Act and Hindu Succession Act.

3. Family Law Lectures by Dr. B. M. Gandhi:
- This book provides a detailed explanation of various concepts of Family Law.
- It covers topics such as marriage, divorce, adoption, maintenance, and custody of children.
- The book also includes case laws and examples to help candidates understand the practical application of family law.

4. Family Law- II by Dr. P. M. Bakshi:
- This book is specifically designed for the UPSC Law Optional exam.
- It covers topics such as marriage, divorce, adoption, maintenance, and guardianship.
- The book also includes previous years' question papers and model answers for practice.

5. Family Law by Dr. U. N. Mitra:
- This book provides a comprehensive overview of various aspects of Family Law.
- It covers topics such as marriage, divorce, adoption, maintenance, and inheritance.
- The book also includes case laws and examples to help candidates understand the practical application of family law.

Conclusion:
These books are highly recommended for candidates preparing for the Family Law section of the UPSC Law Optional exam. They provide a detailed analysis of various concepts and topics related to family law, along with relevant case laws and examples. Candidates should read these books thoroughly and supplement their preparation with regular practice of previous years' question papers to enhance their understanding and score well in the exam.