Obviously the celebration of the 80th birthday of Otto Samuel Knottnerus (1860-1948), location unknown but probably Rotterdam. Photographer is Alexander Jean Alphonsus Antonius Dingjan (1893- 1966). In 1940 he had his studio in The Hague.
For the photo a try.
Sitting from left to right: Otto Samuel Hoogewerff (1910-????), his mother Johanna Jacoba Knottnerus (1888-????) (his father Hendrik Hoogewerff (1879-1932) died in 1932), Otto Samuel Knottnerus (1860-1948), Roelofke van Driesum (1887-????), probably Marinus Wilhelmus Kuyl (1891-????) his wife Harmina Klazina Knottnerus (1892-1940) has died before the photo was taken, Johanna Jacoba Hoogewerff (1913-????), Rudolf Hendrik Hoogewerff (1916-????) standing probably living sun (1929) of Anna Knottnerus (1890-????) en Gerard Pieter Blom (1889-????), Jacobus Constant Kuyl (1920-1969), child of Marinus Wilhelmus Kuyl (1891-????) x Harmina Klazina Knottnerus (1892-1940), Otto Samuel Hoogewerff (1910-1966), sitting his spouce Joke Olivier, Otto Samuel Kuyl (1917-????), Maria Wilhelmina Blom (1919-????), daughter of Anna Knottnerus (1890-????) en Gerard Pieter Blom (1889-????) , unkonwn, Jacoba Ottoline Knottnerus (1889-????) en Adolf Blomhert (1876-1962).
As I said this was a try. Hopefully you have enough family relations now for your further research