1, Parents: Call your in-laws directly by "parents", which means treating your in-laws as your own parents, so as to close the family relationship.

2. Old child: This nickname has a good sense of humor, indicating that although the in-laws are old, they still maintain childlike innocence and vitality.

3. Sweetheart: This nickname emphasizes the attention and care for in-laws, indicating that it is an indispensable part of the family.