ABANDONED. A toy elephant named Jum-Jum

[Christina Stind]

Hey all,
I remember reading this books years ago - probably in the late 80s.
It is either a children's book or a YA.
It takes place during a war. The main protagonist is a young boy who is not with his parents for some reason (I think his mother died) but he has an elephant that he got from his father, I think, called Jum-Jum. Towards the end, he is in a bunker (not quite sure) and his father - as head of the resistance I think - is there too - and they recognise each other because of the elephant.
Does this ring any bells?
Thanks in advance!

Edit: I remember the cover as being grayish - but that was the Danish edition so maybe that's not how it was in other countries ...

[Lobstergirl, au gratin]

Christina left the group. Moving to Abandoned.