I know this is a morbid topic but the reality is I'm going to have to face this in the next two months with my children 6,4 & 3. How have you or would you deal with the loss of a family member to children that age? Is there any way to prepare myself for their needs? We are a very close family and mostly I'm concerned about our children worrying.

I'm sorry, this is a hard one.
I think every parent knows their kids and what their kids can handle.
We have gone through this a lot in the last few years.
Number one importance: is that mom and dad have a strong bond, and are very attentive and loving to the kids and each other during the time of loss.
And, then, just answer all of the questions honestly, even if YOU don't have the answers (what I mean is, answering: I know, sweetie, I don't understand either, but what I DO know is (insert answer) ).
Your kids WILL have fear creep in, it's normal, and for a while you all may be dealing with having to talk over and over about loss, fear, death (the kids will def jump right into "what if mom or dad dies").
BUT, we DID NOT share a lot of details about the illnesses (grandpa had a traumatic stroke, then a few mos later, grandma was very ill for many months, we had a 9, 6, and 3 year old) we did not bring the kids to the hosp, we didn't share details, we just gave general answers, so the kids wouldn't go too far in the imagination. We also knew the trauma of the hosp situation would cause more fear.
We also tried to act as strong as possible with the kids, so they wouldn't be as anxious (mom and dad are okay so we're all okay). I cried sometimes and such, but then we held each other and talked about our sadness and fears. My kids have come through the many losses well, although we had the very tough times of anxieties, nightmares, and such, which are all normal ways kids work out their fears.
We just talked and talked, comforted, had the kids sleep in our room if they wanted (this went on for months and then dissipated), etc. To get them through the hard times.
Just pray about it, you will def know what is good/how much to talk about and share. You know your kids, which ones are anxious, etc, how they deal with stress and fear, so as long as your family bond is strong, and they know that you are "there", they will get through things just fine. And, they will find this a normal part of life (dealing with death). Just do your best to be present to them.
Mostly point them to the Lord, as you turn to the Lord.
I'm sorry I'm so "wordy". I hope you found something helpful in my rambling.
I'll be praying for you all.
Take care

.