Is family members working free on farm owned by family included/excluded in national income?

Yes,

imputed salaries of family members working free on farm owned by family will be included in national income.

Explanation:-

The final goods and services produced in the farm have its market price (value). Thus can be sold in the market market.

It adds to the current flow of goods and services in the economy.

Thus imputed salaries of family members will be included in the national income.