Well because your Nephew's family is not communicative or close... I would not insist to them... on doing what you may want to do.
You/Your Husband.... can, on your own or for your own family... remember him in your own way.... I say this because, it will probably be real hard... to get EVERYONE on the same page about it.. and to agree on it and to feel good about it and some may even feel resentful about it or not want to do what you want to do.... creating conflict in the family.... per such a sensitive subject.... and a very personal one... for your Nephew's family.
The key here is.... your Nephew's family... should be the ones to decide.
Thus, you can, acknowledge the event, as you wish, in your own way....
but not expect all the others to follow suit.
It is, a very personal & private matter, for the Nephew's family/parents....and everyone.... "grieves" differently.... and in different time-lines. Some people may not be able to, nor be ready... to heal yet.... nor feel as you do. For example.
If that were me... I would not want someone, telling me how to conduct this event.... for my child or telling me what to do.
**Adding this: Sorry, I did not mean you are trying to tell others what to do... but others, may sometimes 'feel' that way... especially since emotions are real sensitive now, per your Nephew's passing.
Again, I am sorry, I did not mean... you are telling them what to do.
Put it this way, even with my kids... I just do NOT like it when one of my kids Aunties... tells me what to do for my kids Birthdays. Not the same subject or situation as your Nephew... but, as a parent of my kids... I do not like others telling me what to do with/for my kids... nor how to celebrate an event....
I do understand what you are feeling/saying here in your post... but your Nephew's family... are the one's to determine this. You/Your Husband... can remember your Nephew in your own private and personal way.... as well. Getting everyone to do so and in the same way... just might not be possible... without causing family conflict. And, family conflict... at a time like this... would not be.... something that would honor your Nephew's memory...
All the best,
Susan