Node bundle in Graphviz

Question

I am creating a graph using Graphviz (compiled with neato). This graph contains many overlapping nodes, which is great. However, there is a group of large nodes that I prefer to always be on top of other small nodes - even if I prefer to first identify large nodes on the graph (which causes them to be drawn at the very bottom).

How can i do this?

Edit:
Here is a small example, just to clarify what I mean:

graph G {
    node [style=filled,fillcolor=black];
    BigNode [fillcolor=skyblue,shape=Msquare];

    node [style=filled,fillcolor=red,shape=circle];
    edge [style=invis]
    1 -- BigNode[len=0.5];
    2 -- BigNode[len=1];
}

I would like to BigNodedraw over node 1.

Answer 1

() ...
, node , node, .
, , , , .

:

graph G {
    node[style=filled,fillcolor=black];
    // Definition of BigNode moved to the end of the file
    /*BigNode [fillcolor=skyblue,shape=Msquare];*/ 

    node[style=filled,fillcolor=red,shape=circle];
    edge[style=invis]
    1 -- BigNode[len=0.5];
    2 -- BigNode[len=1];

    // Defined after already defining edges for BigNode
    BigNode [fillcolor=skyblue,shape=Msquare];
}

BigNode node 1

Answer 2

, . neato guide node 6 9. , , : , .