You have the Manthey children born at Kolmar parish, but do you have the wedding there also? It is listed on the Poznan Marriage Project index-- entry #6, 1837 at Kolmar parish-- Johann Gottfried Manthey, age 22 (so b ca 1815), son of Gottfried, married Anna Luise Summer, age 25 (so b ca 1812), daughter of Gottfried. You said previously you didn't have his age or data, but this would seem to give it. Gottfried and Friedrich are interchangeable names in Posen records, I have found.
Apparently he is not directly related to the Carl (Charles) Manthey who married Ernestine Proechel, for Carl was the son of Erdmann Manthey and Louise Erdmann.
I will look at the Samotschin film on Thursday and will check for signs of Proechel births (I expect those) and maybe Mantheys too -- Ken Neumann