Through his mother's lineage he was a first cousin of Erika (Nissen), Ida and Thomasine Lie, and a nephew of Erik Røring Møinichen.
Thomasine married a cousin on the paternal side, famous writer Jonas Lie, and they had the son Michael Strøm Lie who would become Frithjof Plahte's son-in-law.

Frithjof Plahte lived in England as a timber merchant for several years, and some of his children were born there.
In 1876 he bought the farm Nordre Høvik in Bærum.
Here he modernized the farming, and around 1890 he moved the buildings somewhat.
He gave off land for Høvik Church, and other portions of his property were separated out as well.
He bought the farm Fleskum in 1885.
He invested in local business such as Sandvikens Kalkfabrik og Teglverk and Brønøens Kalkfabrik; the latter sparked a prolonged family involvement at Brønnøya.
He was also a board member of Nydalens Compagnie from 1896 to his death.
He died in July 1899.
Through his mother's lineage he was a first cousin of Erika (Nissen), Ida and Thomasine Lie, and a nephew of Erik Røring Møinichen. Thomasine married a cousin on the paternal side, famous writer Jonas Lie, and they had the son Michael Strøm Lie who would become Frithjof Plahte's son-in-law.
Frithjof Plahte lived in England as a timber merchant for several years, and some of his children were born there. In 1876 he bought the farm Nordre Høvik in Bærum. Here he modernized the farming, and around 1890 he moved the buildings somewhat. He gave off land for Høvik Church, and other portions of his property were separated out as well. He bought the farm Fleskum in 1885. He invested in local business such as Sandvikens Kalkfabrik og Teglverk and Brønøens Kalkfabrik; the latter sparked a prolonged family involvement at Brønnøya. He was also a board member of Nydalens Compagnie from 1896 to his death. He died in July 1899.
Frithjof M. Plahte