I assume that you want to know how to perform model referencing in MATLAB R2017a, and in which version was subsystem referencing introduced.
You may use the “Model” block to include a model as a block in another model in MATLAB R2017a. The “Model” block displays input and output ports corresponding to the top-level input and output ports of the included model, called the referenced model. You may refer to the relevant documentation by running the following command in the MATLAB Command Window:
web(fullfile(docroot, 'simulink/slref/model.html'))
If the modelling requirement in your use case is to reduce file contention and merge issues, you might want to consider using a subsystem reference. However, subsystem reference is not available in MATLAB R2017a. It was introduced in MATLAB R2019b. Here is the link to the MathWorks blog post introducing the subsystem reference:
You may refer to the flow chart to help you decide which type of model component suits your use case well here:
I hope it helps!
