We investigate the structure of the code graph of a multicast network that has a characteristic shape of an inverted equilateral triangle. We provide a criterion that determines the validity of a receiver placement within the code graph, present invariance properties of the determinants corresponding to receiver placements under symmetries, and provide a complete study of these networks' receivers and required field sizes up to a network of 4 sources. We also improve on various definitions related to code graphs.• There are distinct sources S, S ′ ∈ S and distinct receivers R, R ′ ∈ R such that e appears in both P S,R ∈ P R and P S ′ ,R ′ ∈ P R ′ .• The parents of v in P S,R and P S ′ ,R ′ are distinct.does not pass through any coding point in G, except possibly in the first edge.Note that coding points are dependent on the choices of edge disjoint paths to each receiver. With G = (V, E, S, R, {P R | R ∈ R}) we denote a multicast network with chosen sets of edgedisjoint paths from the sources to each receiver. For a given multicast network, Anderson et al.[2] define the code graph as a directed graph with labeled vertices that preserves the essential information of the network: Definition 2.3. Let G = (V, E, S, R, {P R | R ∈ R}) be a multicast network and let Q be its set of coding points. Let the code graph Γ = Γ(G) be the vertex-labeled directed acyclic graph constructed as follows:• The vertex set of Γ is S ∪ Q. Given a vertex v of Γ, the corresponding source or coding point in G is called the G-object of v.• The edge set of Γ is the set of all ordered pairs of vertices of Γ such that there is a codingdirect path in G between the corresponding G-objects.In general, Anderson et al.[2] present the following proposition that attempts to outline the properties of a code graph: Proposition 2.4. For any code graph Γ = Γ(G), we have that:• Γ is an acyclic graph.• every vertex in Γ either has in-degree 0, in which case its G-object is a source, or it has in-degree at least 2, in which case its G-object is a coding point.