The following is quoted from Samuel B. Cross: "To be "EI" or "IE"---Which?" (compliments of Faith KEAHEY)

Dear Lisle, You mentioned in your letter of March 3rd, our trouble with the "ie" and the "ei" GREISTs and how to tell which is which. All of the GRIESTs are :ie" except the following:

1. On July 23, 1742, when a warrant for 200 acres in Adams Co. Pennsylvania was issued to John GRIEST of Bethel Twp., it was made out to John GREIST. The write-up about his building "Ye Olde Valley Inn" spells the name GREIST. But his son, John, signed his daughter's marriage certificate on June 9, 1763, as "ie". All other records of that time spell it "ie".
2. In 1872, John Milton GREIST (1850-1906) used the "ei" when he incorporated the GREIST manufacturing Company of New Haven, Conn., but he continued to use the "ie" for patents as late as 1893. About 1881, the children of his brother, Alva Clarkson GRIEST, decided to use the "ei" also. All of their descendants still use the "ei". The line of descent of John M. and Alva C. is (1) sons of Joseph Weirman GRIEST and Ruthanna GARRETSON, (2) of Joseph GRIEST and Susannah PYLE, (3) of John GRIEST of Bethel Twp. and Martha BALDWIN.
3. Wm. GRIEST (1798-1879) and his wife Lydia MILLER, had six daughters and one son, Edwin. The descenants of Edwin use the "ei". The line of descent of Wm. is son of Joseph GRIEST and Mary WEIRMAN, etc., see above.
4. Edwin (of William) was a first cousin of John Milton (of Joseph W.) and both used the "ei". But their other cousins who were the children of Daniel GRIEST and Nancy R. HYMES used the "ie".

The next post is from Henry W. GREIST, cousin #335:

"Mrs. Emma A. GARRETSON_WILLIAMS of Albia Iowa, in your issue of January 1947, asks as to the GREIST and GRIEST families, the orthography, whether the difference as to spelling of the two names would indicate any relationship or visa versa.

They are the same family. The original GREIST brothers, preseumably, two of them, coming from Holland and settling in New Amsterdam (Long Island, N.Y.). During the colonial period, refugees, escaping from Holland because of some political mix-up, spelled their name in the Holland or original manner, the "e" before the "i" as with all Dutch or German names if the "e" be silent in pronunciation.

Later, one of the two brothers migrated to Pennsylvania and became the ancestor of the Western GREISTs. The other remained in the East and I know not his later history.

The Western GREISTs, like presumably some of those of the East, finally altered the orthography of the name to GRIEST, carelessly probably, as was all too common in pioneer days. My Uncle, Mr. John Milton GRIEST, father's youngest brother, a manufacturer in New Haven, Conn., came out to the Indian's during the late '80s, sometime after my father's (Alva C.) death and said: "Our name is constantly mispronounced by educated folk---business men with whom I come in contact, all insisting that the name should properly be pronounced--GREAST or GREEST. So, if my nephews will join with me, we will legally change the orthograpy back to the original form and spell it GREIST. My brother and I agreed and since have used the ancient method, the Holland form, as said, placing the "e" before the "i". And others have followed us in the change, although my Mother continued to use the form used by my father up to the time of his death in 1880.

I am the grandson of Joseph Weirman GREIST (or GRIEST), the husband of Ruthanna GARRETSON of Springboro, Ohio, whose son, Alva Clarkson GRIEST was my father.