The Calendar of the Saints says after her husband was killed hunting she decided to make a pilgrimage to Rome. On returning home she founded seven churches at Ardenne of the Meuse. She also set up an abbey at the same place where she died. 17 Dec is her feast day.

The children left behind by Pippin I included Begga, the wife of Ansegisel.140

After her brother tried to put his own son on the throne of Austrasia, and they were both assassinated, her husband was also assassinated as part of a vendetta against his clan. Begga then retired to one of her domains on the Sambre River and founded the monastery of Andenne.140

The Hull University project on INTERNET refers to her as "Saint Begga". So does Weis' "Ancestral Roots" (190:9)
Pepin of Landen, mayor of the palace to three Frankish kings, and himself commonly called Blessed, was married to a saint, St Itta or Ida, and two of their three children figure in the Roman Martyrology: St. Gertrude of Nivelles and her elder sister, St. Begga. Gertrude refused to marry and was an abbess soon after she was twenty, but Begga married Ansegisilus, son of St. Arnulf of Metz, and spent practically the whole of her long life as a nobleman's wife "in the world". Of this union was born Pepin of Herstal, the founder of the Carolingian dynasty in France.
After the death of her husband, St. Begga in 691 built at Andenne on the Meuse seven chapels representing the Seven Churches of Rome, around a central church, and in connection therewith she established a convent and colonized it with nuns from her long-dead sister's abbey at Nivelles. It afterwards became a house of canonesses and the Lateran canons regular commemorate St. Begga as belonging to their order. She is also venerated by the Beguines of Belgium as their patroness, but the
common statement that she founded them is a mistake due to the similarity of the names. St. Begga died abbess of Ardenne and was buried there.