In 1505, Margaret married her first husband, William Medley, esquire, by whom she had one son, George. In 1509, sometime after the death of her husband in February of that year, she married as his second wife, Thomas Grey, 2nd Marquess of Dorset, the eldest son of Thomas Grey, 1st Marquess of Dorset by Cecily Bonville, Baroness Harington and Bonville. She was styled Marchioness of Dorset upon her marriage. By her second husband she had four sons and four daughters:
Lord Thomas Grey, who was executed together with his brother, Henry, for having participated in Thomas Wyatt's rebellion in 1554.. Lady Jane Grey was also executed at this time, though she had not taken part in the rebellion.
Leonard Grey.
Mary Grey.
Margaret and her husband were part of the group who accompanied Henry VIII's sister, Princess Mary, to France in the autumn of 1514, for the latter's wedding to King Louis XII of France. In October 1530, her husband died and she was given custody of all his property during their eldest son, Henry's minority. On 10 September 1533 at Greenwich Palace, Margaret stood as one of the two godmothers of Princess Elizabeth, daughter of Henry VIII and Anne Boleyn, who would later rule as Queen Elizabeth I of England. Three months earlier, on 1 June, Margaret had ridden in Anne Boleyn's coronation procession from the Tower of London to Westminster Abbey. She was the subject of two portraits by Hans Holbein the Younger.
Quarrels with her son
Margaret first began a long series of quarrels with her son, who had succeeded to the Marquessate of Dorset in 1530, when he was forced to pay a fine of £4000 for breach of contract after he had renounced his betrothal to Katherine Fitzalan, daughter of the Earl of Arundel. As a result, she tried to restrict his allowance throughout his minority which caused much consternation from her peers, who labelled her actions "unmotherly", and inappropriate behaviour towards a nobleman closely related to the King. Margaret only agreed to Henry's marriage with Lady Frances Brandon, niece of the King, on the condition that her father, Charles Brandon, 1st Duke of Suffolk would support the couple until her son reached his majority. In 1534, she felt compelled to answer charges that she was "an unnatural mother". As a result, she offered to contribute to her son's advancement "as my small power is and shall be". Several years later when he came of age, Henry brought his quarrel with his mother before the Kings' Council, where she belatedly admitted that her son's allowance was not "meet or sufficient to maintain his estate", and she offered to increase it. Henry was not appeased, therefore she moved out of the Grey family seat at Bradgate House; however, Henry would not let her remove her personal property, so she wrote a letter to Thomas Cromwell, pleading with him to order her son to release her goods. Margaret died on 6 Oct 1535 at the age of 50.