"Wij hebben een feest morgenavond."
Translation:We have a party tomorrow evening.
As an English speaker translating this sentence, the following distinction occurred to me: "We have a party tomorrow evening." = We are going to a party that someone else is throwing (i.e. we have it on the agenda), while "We are having a party tomorrow evening." = We are throwing a party and having other people over. Which of the two is meant by this sentence (or is it ambiguous), and how is that distinction most naturally communicated in Dutch?
It's ambiguous, however, most people will think that you are going to a party that someone else is throwing. If you want to make sure that you are going to a part, you could say something like 'We gaan naar een feest morgenavond.'. And 'We are throwing a party tomorrow evening' would be 'We geven een feest morgenavond'.
To make explicit that you are throwing a party, say "Wij houden morgenavond een feest." or "Wij geven morgenavond een feest.".
"Wij hebben mogenavond een feest." can have both meanings.