Members of your immediate family can act as your Income Booster: parents, grandparents, siblings, aunts or uncles.
While an Income Booster must be a close family member, they are unable to live in the property.
The Income Booster would also need to meet the same UK residency requirements as the owners. You can find more information on this here.
Everyone's family situation is different. Please reach out if you have any questions regarding Income Booster eligibility.