Her paternal grandparents were Theobald I of Bar and his second wife Ermesinde of Brienne.

Margaret brought Henry Ligny-en-Barrois as her dowry, however, by a clause in the marriage contract, it remained under the feudal suzerainty of the county of Bar.

In contempt of this, Henry paid homage in 1256 to Theobald II of Navarre, in his capacity as Count of Champagne.

Margaret's brother, Theobald II of Bar, took advantage of the conflict then raging between Frederick III of Lorraine (their cousin) and the bishops of Metz.

On 8 September 1268, King Louis IX arbitrated between the two counts and Henry was freed and repossessed of Ligny, but under the suzerainty of the Barrois.