"I'd also say having Jack's son Chris living with us from his 13th year on helped in raising Rick"

Marie Windsor's quote recommends that having Jack's son Chris dealing with them from his 13th year on was useful in raising Rick. This implies that Chris was a positive influence on Rick, and that his presence was advantageous in assisting to raise him. It might be that Chris was a good example for Rick, or that he supplied a sense of stability and security for Rick. It might likewise be that Chris had the ability to provide assistance and recommendations to Rick, or that he was able to help Rick with his studies or other activities. Whatever the case, it appears that Chris was a vital part of Rick's upbringing, and that his existence was useful in helping to raise him.