Becoming the godmother of your younger sister may seem the perfect blend of love and responsibility, but whether you can accept this responsibility depends on your age and situation in life. In the past in the Catholic Church, it was understood that godparents would become the legal guardians of the child in case of the parents’ untimely death. This is rarely the case now, but it is an important point of clarification if you are the sibling of the baby being baptized. According to the Debrett’s Etiquette website, a child traditionally has three godparents, girls having two women and one man. Being one of two godmothers forms more of a safety net in terms of both the child’s spiritual guidance and physical care. Whether or not the child’s godparents are to also be legal guardians needs to be clearly defined in a will or trust.

Becoming the godmother of a younger sibling also depends on your age and relationship to the Catholic Church. According to the Catholic Education Resource Center, potential godparents must have completed their 16th year unless other provisions have been made by the Bishop. Godparent candidates must also be active in their own faith and have received Holy Eucharist and confirmation. It is also important that you have an active relationship with the church, regularly attending services. If all of the necessary conditions are met and your parents feel you would be a good godmother to your younger sister, they are free to choose you.

Taking on the job of godmother for a younger sister means more than just accepting vows at baptism. People chosen to be godparents at baptism are also expected to be sponsors for confirmation. This connects you to the spiritual health of your godchild from birth to adolescence and beyond. As the sister of the infant being baptized, you take on double the responsibility, as you are now not only a sister and role model but also a spiritual guide. The Catholic Doors Ministry website article "The Role of the Godparent" encourages parents to choose godparents who have a growing faith, high moral character and willingness to guide the child towards salvation.

Although the original purpose of godparents was to help parents nurture their children spiritually, today’s godparent often takes on a different role. Godparents are chosen as life-guides for infants who can actively influence the child’s life in positive ways outside of religious instruction. If your parents' idea for godparents is more along this line, and you are old enough to make this kind of care commitment to your younger sister, there is nothing preventing you from assuming the role. In the Birth.com.au article "How to Choose Good Godparents," Joanna Bounds, editor of the British magazine "Mother & Baby," suggests being involved in your goddaughter’s life by passing along the love of things you are passionate about, helping her through the turbulent teenage years and generally being a positive figure in her life.