Teuntie van Teutem is op 18.1.1767 in Rotterdam (Geref.) gedoopt als dochter van Hendrik van Teutem en Elizabeth van der Stok - getuigen waren: Fredrik van Teutem en Teuntie Brink. "Op de Kipstraet".
Well, that is going to be a difficult task, since (legal) privacy rules at this forum say that we can only discuss people proven to be deceased, or have been born at least 100 years ago. And your objective is to find living relatives.
So we know 2 brothers have died in the 2nd world war: Frans Maurits (of whom you have the object) and Frans Adriaan. They were both not married. So if one of them would have had any offspring it would be very difficult to impossible to figure that out.
Fortunately, it seems they had a younger brother. I will not mention him here because of privacy rules, but send you a private email with the very limited data I have been able to find. Unknown if he is still alive, got married, had any children, etc.
If I look at the family one generation back (uncles and aunts) we are lucky to have this ad from 'De locomotief", 30-05-1930:
Quick research will learn:
A. E. Jacobs-Maronier = Aletta Eveline Maronier, born Tegal, july 20th 1882. Married Karel Louis Jacobs, Bandoeng, may 14th 1915.
L. M. C. van Aalderen-Maronier = Louise Martina Cornelia Maronier, born unknown. Married Willem Rutger Henri van Aalderen, Sourabaya, august 17th 1907
J. H. Maronier is already discussed above, and F. A. Maronier is the father of the 2 sons.
It appears that Jaap Deelstra who published "Stamboom Deelstra, Balk, Van den Bos en Kamphof" does know the identity of 3 grandchildren of Louise Martina Cornelia Maronier and Willem Rutger Henri van Aalderen. These must now be elderly people, but may still be alive. See this page of his publication. You may try to contact him, or via the link (name just above here) to his personal page.