I'm sorry that on top of your loss you need to be involved in this. I do think that as the only 2 grandchildren they should be in the family limo. I understand not making waves at this time so I would get the second limo and ride with your boys. If you think that's going to upset the apple cart, just go with your boys in their car, they need their mom through this and frankly your DH should be putting his kids ahead of his sister and see this.