SIL between external source code & Simulink model

[Background]

I got sourcecode which generated base on Embedded Coder.

It also modify by stakeholder's internal tool which I didn't know what change item on those source code

(Maybe source code structure change : data declaration , file & folder structure)

[Question]

1) How can I adopt Simulink Test-Test Manager to perform SIL between those source code & simulink model?

2) if you are any suggestion, please feel free to advise me