We have various references that allow us to say for sure that Ted Sandyman was extant in both III 3018 and III 3019 (or 1418 and 1419 by the Shire-reckoning) but little beyond that. We know that his father was still operating the Old Mill until Sharkey's occupation of the Shire, implying that Ted was relatively young at this point (though in Hobbit terms 'relatively young' might easily suggest an age of fifty years or so). Of his ultimate fate we have no account.

In normal use, the shortened name 'Ted' can abbreviate either 'Edward' or 'Theodore'. 'Edward' comes from Old English, while 'Theodore' comes from Greek, so of the two 'Edward' is by far the more likely as a Hobbit-name. Of course, it is entirely possible that 'Ted' here stands for some other name unique to the Hobbits (in the same way that 'Sam' is short for 'Samwise' rather than 'Samuel') but, if so, we're offered no clues as to what that name might be.

The name 'Sandyman' is not explained, and neither is it used as a real surname, so any interpretation is speculative. It may be connected to the Sandymans' occupation as millers, perhaps jokingly suggesting that they would be dusted with the flour of their mill, as if covered in sand.