Does the prayer spot become impure if a girl who cleans herself with tissues from impurity sits there during prayer, and must the diaper of a child who passes by the prayer spot be changed before prayer, knowing that their outer clothes are clean?

A child passing by a worshipper, or touching him, or sitting next to him, or in his place of prayer, does not affect the validity of the prayer, unless impurity is transferred to the worshipper which would affect his prayer. However, if the worshipper carries the child while the child is covered in impurity, then his prayer becomes invalid because he is considered as carrying impurity. Furthermore, the child's diaper should be changed before prayer if there is a possibility of impurity from it reaching the worshipper.