We're not sure here at Toobworld Central, but master spy Oliver Mace could have fathered several children. Although they weren't seen in the Kate Bush video for "This Woman's Work", they could have been staying with a relative while their parents had a quiet romantic dinner at home. (Which sadly ended in tragedy.)
If he did have children, it could be that Oliver Mace (aka "Stephen Fischer") founded the family tree which led to Mr. Klineman Halpen.
Klineman Halpen was the Chief Executive of Ood Operations, a job that had been passed down from his grandfather, to his father, and eventually, himself.
Because he kept drinking what he thought was a hair restoration liquid supplied by his supposedly loyal Ood servant Sigma, Halpen eventually turned into an Ood himself.
The family tree of Halpen could have another branch in the distant past, one which eventually links to yet another TV series set in the late 1950's. But I'll reserve mention of that for when I get a decent frame grab for it......