Fellowes in 1695 married Mary Martin or Martyn, daughter of the London merchant Joseph Martyn. They had four sons and two daughters:
William Fellowes (MP, died 1804) was their son. • John Fellowes (1712–1714). Martyn was a sugar merchant in Love Lane. He had spent time on
Nevis, and acted as London agent for the
Leeward Islands planters. In 1696
John Oldmixon, in financial difficulties, took out a mortgage on a family property, the manor of Oldmixon (now part of
Weston-super-Mare). The mortgage was with Martyn and Fellowes. Oldmixon not exercising a redemption option, they took legal control of the property in 1699. In 1703 Martyn, Fellowes and Thomas Andrews, another son-in-law to Martyn, acted as executors to Martin Madan, slave-owner on Nevis, and father of
Martin Madan the future Member of Parliament. Martin Madan of
Northill took out a mortgage with Martyn and Fellowes around 1699. ==Notes==