Bettina Anderson was already well-known in Palm Beach, Florida, for her fashion modeling, her passion for environmental conservation and charity work, and for being from a prominent banking family.

For the third time in his life, Donald Trump Jr. found a partner in marriage − and soon, they'll say, "I do."

The couple exchanged vows Saturday during an intimate ceremony on a private island attended by roughly 40 guests, including Don Jr.'s five children and several members of the Trump family, including I...