i think that they want to look at how much the natural parent is benefitting from the marriage. At this scenario, step parent makes 6x as much as natural parent and has 5x the assets. because there are going to be some shared bills, I think that dad would be assessed a minimum 25/30k based on his income/assets vs an automatic full pay when they look at family income of 700k. While they may not necessarily be looking at a contribution from the step parent, they will look at the overall strength of the family finances for bio parent to pay.
In this situation, Harvard states:
so dad would be assessed have 250k