Ælfflæd was married to Byrhtnoth, who probably succeeded her father as ealdorman of Essex.
Æthelflæd and Ælfflæd were Ælfgar's heirs at his death, some time between 946 and 951 based on the dating of his will, S1483.
Æthelflæd married Edmund following the death in 944 of his first wife Ælfgifu, mother of the future kings Eadwig and Edgar.
Records of Ely Cathedral, to which she, her sister, and her brother-in-law, were generous benefactors, say that she then married ealdorman Æthelstan, probably Æthelstan Rota.
In addition to gifts to Ely, the will endowed Glastonbury, Canterbury, Bury, and the family monastery of Stoke-by-Nayland.