Nelly Millin had earlier paid in most of the contents of the boxes - about pounds 33,000. Yesterday she undertook to surrender the balance, thought to be about pounds 3,000.
The row between Mrs Millin and the fund began because she collected money outside the north London boroughs of Barnet and Enfield, where she was a voluntary county organiser.
Fundraisers in adjoining areas, including Hertfordshire and Essex, complained she was undermining and confusing their activities. She also insisted the money donated to her and her collectors should be spent in her area.
Mrs Millin was taken to court after repeated requests for the return of the boxes failed.
At a private hearing in the High Court in London yesterday, the former breast cancer patient - who says she owes a lot to the care and counselling of Macmillan nurses - pledged that she would no longer claim to be an authorised collector for the fund.
In return, the fund promised to give 'due consideration' to her views on how the money should be spent.
Paul Rossi, the fund's secretary, said Mrs Millin 'was a very good collector who raised a lot of money, but she would not stay in the area we asked her to stay in'.
Mrs Millin said she would fight for the right to run an autonomous charity in support of Macmillan nurses.