I agree - honesty with kindness is the best way.

Unfortunately I had to tackle this subject multiple times and from a very early age with my DS.

When he was 2, I had to explain why my friend wasn't pregnant anymore and why he couldn't cuddle the new baby.
I had to repeat this exact same scenario 6 months later with another friend.
Then, my best friend passed and I had to explain to him how, why and what happened to her after.
He was 3.
So, now, he understands that Death is a part of life, and unfortunately it happens.
I did have to reassure him though that I wasn't going to die straight away and that I hoped to be old and wrinkly and grumpy before I passed!

Just as a point of interest - DS now adores telling everyone what a special name his new baby sister has (her 1st middle name is the name of my Best Friend who passed in 2001)

I hope you have found an answer that will work for your family Mumma!