Dear Chavah,
Doing research on the Claus-family I also have an Aaltje Sjamaar in the pedigree. Aaltje was baptised in Amsterdam 13 march 1796 and was a daughter of Benjamin Sjamaar and Aaltje Galois. I do not have any other dates on her. She married Stephanus Claus in The Hague on 21 May 1817. She and her husband had 11 children.
Greetings,
Gert Scholten
Amsterdam
The Netherlands