The relationship between cattle egrets and cape buffalo would not be commensalism if the egrets removed ticks from the buffalo, because both species would benefit. The buffalo would be tick free and the egrets would have food to eat.
Commensalism is where one animal benefits from the relationship but the other doesn't. Oxpeckers feed by picking ticks and parasites from the rhinos hide, and the rhino benefits by having annoying parasites removed, so the relationship is symbiotic - they both benefit.
Your first cousin's daughter is your first cousin once removed. Her grandadaughter is your first cousin twice removed. Your second cousin's daughter is your second cousin once removed. Her grandadaughter is your second cousin twice removed. And so forth. It gets more complicated if you start with a cousin once removed , or twice removed, etc., two possibilities for many such relationships.
You have a genetic relationship with every first cousin, whether once, twice or 15 times removed. The further removed the slighter the relationship.
The atom is then considered an ion :)
cousin once removed
The son of your First Cousin Once Removed, is your First Cousin Twice Removed.
The child of your first cousin, once removed, is your first cousin, twice removed.
You can't have a grandfather 5 times removed. You could have a 5Great grandfather. In which case the relationship would be your 3Great Grandfather.
Your grandfather's cousin is your cousin twice removed. Her husband has no direct relationship to you.
You are first cousins once removed.
The son of your first cousin, twice removed, is your first cousin, thrice (3 times) removed.
She has no relationship with your step-daughter. They do not share a common ancestor. If you adopt her, they would become second cousins once removed.