Margôt was Leader of the Young Members Department of Mothers' Union (YMD) in Tweed Heads Parish and in 1963 became Grafton Diocesan Leader. At this time YMD was very active, there being 18 groups in the Diocese.

In 1969 Margôt became Diocesan President of MU Grafton and continued in this position until 1978. She was President during the time of New Dimensions when MU went through a period of soul searching about membership conditions, its aims and objects, and autonomy. The Commission took three years to investigate all aspects of MU and under Margôt's leadership, Grafton put in its share of suggestions and answered questionnaires.  

When Marjorie Hawkin, Editor of Mia Mia, resigned in 1976 Comonwealth President Mrs Olwyn Jull asked Margôt to accept that position which she held for four years. Then in 1980 she was elected Commonwealth President, the first time a member of Grafton Diocese had held the office, and in 1983 she was re-elected for another three years. In 1979 a World Council Meeting was held in Brisbane for two weeks and Margôt was a member of the Committee organising this wonderful event.

During her time as President one of Margôt's concerns was the need for MU to look to the needs of aboriginal women and she felt that MU should be training a person to work amongst her own people and a training fund for an Aboriginal Worker was set up, to which members were asked to contribute $1.00 each. She travelled widely visiting members all round the country. She was always interested in branch members and believed these were the important ones, she kept in regular touch with Diocesan Presidents, and drew up notes for Department Heads on their responsibilities.

During her last term Margôt developed cancer but continued to work and was still in office when she died on 18^th March 1986, a great blow to her MU family. Her funeral in Sydney was very well attended and a Thanksgiving Services was held in Grafton Cathedral. At Commonwealth Council later that year it was decided to set up a fund - "The Margôt Sanders Memorial Fund" in her honour, the interest to be used for promotion of MU and this was also followed by Grafton Diocese. It was also at that Council Meeting that it was decided to change the name from Commonwealth to Australian Council.

Australian President Margôt had also been Australian President of GFS from 1972 to 1975, the only person who has been Leader of both organisations at National level. In 1975 she led a party of GFS Leaders and others to England to celebrate the centenary of GFS.