This is a topic I know only too well. I lost my mother at a young age. My mother was only 26 yrs old. My family was ill prepared for this circumstance. Thankfully a family member had a cemetery plot they gave us. So you see, I know what it is like to lose a parent and the needs that go along with that situation; big and small.
You have to be very careful in how you treat these boys. Honesty, going too far makes us very uncomfortable. There were some people that acted extremely different to me (sometimes people to this very day still do) and I didn't even want to be in the same room with them. Most people, thank the good Lord, will never know what it is like to be that scout, myself or others like us. Because of that though, most people don't know how to behave round us.
Those of us who have gone through this type of tragedy are touched by people's support. But there is a limit. Going too far makes us feel separated from everyone else. That is the last thing that anyone intends but it happens. I have personal experience from my own childhood with people bending over backwards to make me feel included but most times it worked out just the opposite.
You'd also be surprised how uncomfortable some people get round child who have lost a parent too early. These people will try to disassociate themselves as much as possible. Sometimes these people are family members, who think the child reminds them too much of the lost parent. My father did just that.
At the funeral/wake, let the family know you are there no matter what time of day or night. But otherwise, treat them all the same as you did yesterday. Stand back and watch for a "need" to present itself. Then if you can, fulfill that need. Maybe when the stores have their school sales in a couple months, talk to the father and ask him as long as you're at the store for your children if he wants, you can also grab some things for his boys.