Those who observe Ekadasi fasting should not partake any food after completion of shraddham and they should continue their fasting.
Notes:
Towards the end of the shraddham, instead of performing prashanam, for those who are fasting, a ritual called avaghraanam is prescribed. In this, after pinda pradhanam (offering of balls of cooked rice to the pitrus), a small portion of prasadham is taken in hands and smelt by those who observe fasting or those who partake palaharam only. After smelling the prasadham, it must be thrown away as it is made of rice.
Those who are able observe total fasting, should do so. Those who are unable to, must not partake anything that was not prepared as offerings specifically for the shraddham. From among the shraddham offerings, they must avoid offerings made of cooked rice and can partake cooked vegetables, other offerings.