Wish, it seems like you are coming from a loving place, and you're sad at the apparent loss of the relationship the parents had previously with the family.
I don't think this is something you can fix, or deal with, or make better. Equally you need not govern your choices based on what you feel will make things worse.
Their avoidance and perceived ignoring or not acknowledging family babies is up to them. You can't make them change to behave in a way you are all more comfortable with.
If it's any comfort, think of it as having had a bomb go off in the middle of the family, with them at the centre of it. It's a battle even to survive, and a lot of irreparable damage has been done, more at the centre, but also spreading outwards from the main blast. It is not the responsibly of those closer in to make their hurts less visible to those further out in order to reduce their pain.
Time will heal a lot of the awkwardness. Two years is barely enough time for them to be able to contemplate the continuance of life and feel that they may one day not feel destroyed every moment of every day.
The way for you and your family to deal with it is to accept their choice to be less engaged with their wider family life. The more you push, or persuade, or make them feel that they are the cause of hurt, the more that will pull away out of self preservation. You shouldn't underestimate the need to pull in your horns and hide away from everything and everyone, even well meaning people whom you love very much.
I know it's hard for you to accept, let alone understand, but please try again to hear what people are saying.