Frankly speaking, it's a BIG BIG BUG of VM2.
It seems developpers don't know what is trade at all.
Do you know that every color, every size of product has it's own SKU?
So, the task of Child is to do this thing. Noootttttttt CUSTOM FIELD. It's a different at all.
Strange that VM 1.1.9 works nice with Childs.
Just look an example and difference in selecting

It defenetly should be option to show child in parant product details or no.
Now I use as Milbo wrote
http://forum.virtuemart.net/index.php?topic=98648.0Sorry, but it's a little bit bullshit.
Look here, I explain.
My supplier for example gives me a price.
product_name1 SKU_1 total 15 in stock
this product has several sizes and colors. Let's take only sizes for example.
product_name1, SKU_1xl, Size: XL, price: $100, in stock: 6
product_name1, SKU_1m, Size: M, price: $80, in stock: 4
product_name1, SKU_1s, Size: S, price: $60, in stock: 5
So, what I have in my shop if I use Generic Child Variant.
I have 2 drop down lists: first is Generic Child Variant, second is the Size. But customer can't choose the size. Customer can choose only Generic Child Variant.
But the first choice is a product_name SKU_1 (it's a general name, not a feature)
Do you see the difference?
VM 1.1.9 works good with it, but not VM2.
Who wants a Child in a category like a separate product?

What is the meaning of this? It's easier to create one more product and show it in a category then to use a Child. These schema works very good in mogento shop when you combine products there by their features (size, color and so on).
So, please, think over, VM2 shouldn't go against the traditional trade rules.
Now it has many useful features, so to fix this BUG it's very important.