System and method for creating and executing a graphical program. A first plurality of graphical program elements (GPEs) having a first model of computation (MoC), e.g., homogenous dataflow, are assembled in a graphical program in response to first input. A structure, including an interior portion, is displayed in the graphical program, indicating use of a second MoC, e.g., multi-rate dataflow, for GPEs within the interior portion. A second plurality of GPEs having the second MoC are assembled within the interior portion of the structure in response to second input. The second plurality of GPEs are converted into a new third plurality of GPEs having the first MoC, e.g., by parsing the second plurality of GPEs to determine multiple primitives according to the second MoC, determining the third plurality of GPEs based on the primitives, and assembling the third plurality of GPEs in the graphical program.