Mike,
A German correspondent has told me more about my German Pelster ancestors. It is a long shot, but perhaps some of this information will help you.
1) Garrot Pelster was probably not Garrot in Germany--more likely Gerhard or Gerd. To my ear, Garrot sounds very much like Gerhard.
2) Garrot's son..my ancestor..John Henry Pelster (Johann Heinrich in Germany) was married in Twistringen in 1852 which is an interesting coincidence considering your Gesina was emigrated from Twistringen. The priest wrote Pilster instead of Pelster in the marriage book.
3) Garrot Pelster was supposedly born in Everswinkel(Ostberven) which is about 80-100 miles from Twistringen. I am not sure how John Henry ended up in Twistringen to marry (military maybe).
4) Is it possible that your Gesina was originally from Everswinkel?
Kathy