This photo is no way 1943. Nonsense!
This must be an early photo. The older lad is wearing the light-brown
shoulder-straps; the youngest has not even the one. I think the photo
is from about 1933 or latest 1934.
The knife is a look-a-like as the Buschmesser. It is not a Winu-Fahrtenmesser,
and as offered in spring 1933. I have such knives in a sales catalogue from
that period.