A woman in a fur lined plaid purple jacket stands by a table full of eating children.
A woman wears a plaid jacket as she stands near children sitting at a table.
A woman wears a plaid jacket is part of the description of her wearing a fur lined plaid purple jacket as she stands by a table full of eating children which means the children must be sitting.
A plaid jacket purple jacket tells the color of the plaid jacket.
If the children are at a table eating, it follows that they are sitting at the table.