Would helping a sister in need with her children's education be considered Sadaqa Jariyah (ongoing charity)?

Your charity to your needy sister is an act of devotion and obedience for which you will be rewarded. It is better and greater in reward than charity given to others because it combines charity and maintaining kinship ties. However, it is not considered an ongoing charity (Sadaqa Jariyah), as ongoing charity is an endowment (waqf).