如何在两个节点之间的箭头顶部的Graphviz中添加3个项目符号？

我试图用Graphviz创建一个神经网络图。所以基本上我想在Dropout 1和LSTM 4之间留出更多的空间，并在箭头3的顶部添加项目符号，以指示有更多的层重复。另外，由于我总共有50个节点，我想在前两个红色节点和第三个节点之间留出空间，并在那里添加要点。希望我能说清楚

我试图创建的图表我用油漆画了间距和项目符号

digraph G {
    rankdir=LR
    splines=line     
    node [fixedsize=false, label=""];

    subgraph cluster_0 {
        color=white;
        node [style=solid,color=red2, shape=circle];
        x1 x2 x3;
        label = "Input layer (60,1)";
    }
        subgraph cluster_1 {
        color=white;
        node [style=solid,color=blue4, shape=circle];
        a12 a22 a32;
        label = "LSTM 1 (60,1)";
    }

    subgraph cluster_2 {
        color=white;
        node [style=solid,color=blue4, shape=circle];
        b12 b22 b32;
        label="Dropout 1(0.2 probability)";
    }
subgraph cluster_7 {
    color=white;
    node [style=solid,color=blue4, shape=circle];
    c12 c22 c32;
    label="LSTM 4(60,50)";
}

subgraph cluster_8 {
    color=white;
    node [style=solid,color=blue4, shape=circle];
    d12 d22 d32;
    label="Dropout 4(0.2 probability)";
}

subgraph cluster_9 {
    color=white;
    node [style=solid,color=red2, shape=circle];
    O;
    label="Dense(1)";
}
    
        x1 -> a12;
        x1 -> a22;
        x1 -> a32;
        x2 -> a12;
        x2 -> a22;
        x2 -> a32;
        x3 -> a12;
        x3 -> a22;
        x3 -> a32;
    
        a12 -> b12;
        a12 -> b22;
        a12 -> b32; 
        a22 -> b12;
        a22 -> b22;
        a22 -> b32;
        a32 -> b12;
        a32 -> b22;
        a32 -> b32;
    
        b12 -> c12;
        b12 -> c22;
        b12 -> c32; 
        b22 -> c12;
        b22 -> c22;
        b22 -> c32;
        b32 -> c12;
        b32 -> c22;
        b32 -> c32;
    
        c12 -> d12;
        c12 -> d22;
        c12 -> d32; 
        c22 -> d12;
        c22 -> d22;
        c22 -> d32;
        c32 -> d12;
        c32 -> d22;
        c32 -> d32;
    
    
        d12 -> O
        d22 -> O
        d32 -> O

}