"Capt. Forbush's land and dwelling were north of the Dr. Hawes place, and near what is now East Maine Street in Westboro." (Pierce).
Note that with us missing a birth date for this SF, a death date for him or his father, no death date for Abigail Rice, and unclear as to which SF Sarah C married, it is possible to conflate this Samuel and his father as has been done in the Forbush Geneology, Reed Collection, Westboro MA Library. Could the key be in the will in Probate records, Worcester, mentioned by Pierce (witnessed by Eb,Lucy and Thomas F). Land N. of Dr. Hawes place near E.Main St. in Westboro. We also have will 5/28/1758 was proved 12/16/1767.
"Lt. Samuel Forbush married Sarah T(...).1 Lt. Samuel Forbush died on 10 October 1767 at Westborough, MA.2. Your (RICE) authors note that an extensive line of descendants has been found for Samuel and Sarah Forbush of Westborough. Unfortunately, the identification of Samuel as the son of Samuel and Abigail (Rice) Forbush of Marlborough is only tentative at best. We therefore omit the descendants until the connection is established."