During the time of Tryntje Sybolts 2nd marriage to Jan Hulst, a son was born: Sibolt Jans, born on 8 Aug 1777 in the city of Groningen. 

Sibolt Jans died 25 Oct 1816 in Groningen: he was 39 years old, according to the Overlijdensregister Groningen 1816
Aktenummer 591.  Mentioned in the register is Sibolt's wife, Lammegien Breedveld. 

Sibolt Jans and Lammegien Breedveld were married on 6 May 1809 at Groningen.  Lammegien was the widow of Berend Wybolts. 

This union produced a daughter, Catharina Jans, born 11 Jan 1811 at Groningen.  She was baptized Catholic (Kerkeboek Groningen 1795-1811
Collectie DTB (toegang 124) Inventarisnummer 637 (Rooms-katholiek).

This union produced a second daughter, Jurriana Jans, who died at 19 months on 23 Nov 1816, also in Groningen (Overlijdensregister Groningen 1816 Aktenummer 720).

What follows is the death record of Sibolt Jans, half-brother to Jacob Cornelis Kruize.

And below is the death record for Sibolt's daughter Jurriana, who died not even a month after Sibolt.

You will note the signature of Roelf Roseboom on the above documents.  Who was Roelf?  Roelf is the tie-in to Hindrik Roseboom, the 3rd husband of Tryntje Sybolts.  Roelf was the son of Hindrik Roseboom and an earlier wife named Geertruid Roelfs.  Roelf died 27 Sept 1824 in Groningen.

And the birth record for daughter Jurriana.

Further Proof: Early Marriage Record for Hindrik Roseboom and Geertruid Roelfs.