When talking about more than one Delta, it should be Deltas.
All of the Deltas are wearing red today.
When talking about one Delta and something that belongs to her, it should be Delta's.
That Delta's umbrella is cute.
When talking about more than one Delta and their possessions, it should be Deltas'.
Those Deltas' cars are blocking the entrance to the community service site.
Live it.
Love it.
Embrace it.
