Those who came before (our ancestors, our parents, our older siblings, the founder of a company or organisation, employees who have been there longer…) have a priority over those who came later and need to be respected.
Coming first does not mean being more important or better. It is simply that there are different places that have to be respected and often there comes also a different level of responsibility.
When a couple decides to marry and they have children, they create a new system. And this system comes before their respective previous ones, however the previous systems (families of origin) have to be honoured.
Parents take precedence over their children; the first child has precedence over the second and so on. / the ranking between parents is defined according to their function. They always work in the service of each other / When a child dies the order of priority remains untouched.
Children from a first relationship come before the new partner and before the children from a second relationship.
New partnerships take precedence over former ones (even when during a marriage one parent starts another relationship and a child is born from this relationship, this newly founded family takes precedence over the earlier one). What however we always have to remember is that the former partners are still part of the family system and they have to be honoured and acknowledged as the first ones.
A very special thing when it comes to priority is the case of adoptions. The rightful place for that adopted child is always after the youngest child, despite age.