The Pilgrims were beaten 3-2 at Altrincham on Friday afternoon.
Slater had handed the Pilgrims an early lead - with Sheriff on target in the 77th minute.
Boston (3-4-2-1): Jake Lovelace; Oskar Rajski (Josh Doran 60), Owen Sheriff, Taylor Jaine; JJ Ward (Jake Higginbottom 65), Jake Henderson, Han Stevens, Lucas Stubbs (Kyle Featherstone 78); Jack Waddington, Rueben Fogg; Flynn Slater.