I understand your logic and I don’t know how prevalent these cases of people marrying/divorsce/remarry, etc. are these days but looking at my own collection of nearly 400 people, I counted 2 instances where I need to define step parents and step brothers/sisters.
To cater for this scenario of people having multiple marriages, I’m having to add the father/mother multiple times of all the children, or add parents multiple times for the children, add siblings multiple times for each of the children, and so on, and to be frank this is very cumbersome and not sustainable.
There must be a way to say OK these 2 people are married once (with some sort of a toggle switch) and the children added for one parent should apply to the other parent, and the children are all siblings of each other.