Berenice I of Egypt in Harpers Dictionary of Classical Antiq
The granddaughter of Cassander, brother of Antipater. She married Philip, a Macedonian, probably one of the officers of Alexander, and became by him the mother of many children, among whom were Magas, king of Cyrené, and Antigoné, whom she married to Pyrrhus, king of Epirus. She followed into Egypt Eurydicé, daughter of Antipater, who returned to that country to rejoin her husband, Ptolemy I. Berenicé inspired this prince with so strong a passion that he put away Eurydicé, although he had children by her, and married the former. He also gave the preference, in the succession to the throne, to her son Ptolemy, notwithstanding the better claims of his offspring by Eurydicé. Berenicé was remarkable for her beauty, and her portrait often appears on the medals of Ptolemy I. along with that of the latter.
Berenice I of Egypt in Wikipedia
Berenice I (c. 340 BC-between 279-274 BC) was a Greek Macedonian noblewoman and through her marriage to Ptolemy I Soter, became the first Queen of the Ptolemaic dynasty of Egypt.
Berenice was the daughter of an obscure local nobleman called Magas and Antigone . Her maternal grandfather was a nobleman called Cassander who was the brother of Antipater  and through her mother was a relation to his family.
In 325 BC, Berenice married an obscure local nobleman called Philip . There is a possibility that Philip may have been previously married and had other children. Through her first marriage, she bore Philip: daughter Antigone who married as one of the wives of King Pyrrhus of Epirus, son King Magas of Cyrene and possible a third child a daughter called Theoxena .
Magas dedicated an inscription to himself and his father, when he served as a Priest of Apollo . Pyrrhus gave her name to a new city called Berenicis. Philip had died.
Second Marriage to Ptolemy
After the death of her first husband, Berenice travelled to Egypt as a lady-in-waiting for her mother’s first cousin Eurydice who was the wife of Ptolemy I. Ptolemy I was one of the generals of King Alexander the Great and founder of the Ptolemaic dynasty of Ancient Egypt. Ptolemy I caught the eye of Eurydice’s cousin, whom he later married in 317 BC. Berenice bore Ptolemy I: a daughter Arsinoe II of Egypt, a son Ptolemy II Philadelphus and a daughter called Philotera .
In an unknown Olympiad, she was a victor in the chariot races. Ptolemy II was recognized as his father's heir in preference to Eurydice's children to Ptolemy I. A port was built in the Red Sea and it was named Berenice. After she died, Ptolemy II and later Ptolemy IV Philopator decreed divine honors to her (Theocritus, Idylls xv. and xvii.) .