Wielkopolskie Towarzystwo Genealogiczne GNIAZDO

Hello !
I am doing the paternal side of my family tree.
My ggrandfather was Martinus Braciszewski b.around 1824 in Slawno ,Wielkopolskie,Poland.
He married Cecelia Koteras,b 1821-1823. Her father's first name, Petrus.
They were married in Slawno,1849 per Poznan Project.
They had 3 children,Marrianna,Rozalia and Martin.
I am looking for death certificate of Martinus or grave,as he did not immigrate to the US with his family and they came to the US at different times.
Other things---Rosalia married Joseph Prus in Miescisko in 1879.Marrianna married Stanislaus Stelter in 1872,Popowo Koscielne.
Martin (son) and his mother Cecelia came to the US together on the Fulda in 1883-1884. She was 52 and he was 16.Moved to Buffalo NY and Martinus stayed in Poland.
I can't find any more abt him,maybe he died in Germany .But I figured since they all lived in Poland, around Slawno,he would be buried there.
Can you help find a record of his death and/or where he was buried ?
Kind Regards,
Marie

All parish registers for Sławno are available here:
https://www.familysearch.org/search/cat ... %20Library

_________________
Piotr Lis

Burzyński i Kotecki (Kociałkowa Górka, Czerlejno)
Błażejewski (Krzywiń), Dubisz (Strzyżew, Bieżyń)
Baranowski (Jurkowo, Rąbiń), Bukowiecki (Jurkowo)
Szuleta (Wrząca i Racławice), Kurzawa (par. Goszcz i Giżyce)