There are various opinions regarding the husband and wife passing very small children and attending to the child when the mother is holding the child. The root of the issur (prohibition) of the husband and wife eating together on one table or one plate is that it might lead to touching. There has to be a visual heker (reminder) between the couple during a meal, or even during an informal eating or drinking session, according to some opinions. The opinions regarding this heker object range from it being something very small and flat like a ring, to an item with a clear height. It should also be something new and distinct on the table, not a usual object that is on the table. The minhag is that if there are family members or guests at the table, a heker is not needed. The poskim are meikel (lenient) when the husband and wife are at a large enough table that they cannot reach each other.