Usage in a larger context

[alexanderscheible]

First, thank you a lot of the great work!

I am considering using your library in an existing and bigger application.
As far as I understood, the libraries assumptions fit our problem perfectly, however I see the following problem and would appreciate your opinion.

We can parallelize our problem as shown in the following picture:

Now the problem: Is it possible to use the functions (e.g., function C or method A1) in your parallel context without extensive reorganization of our code?
The methods and functions are usually declared and defined in separate headers and source files.
The only solution I see right now, would be to reimplement the (member) functions as free lambdas and provide the non-parallel versions, or member functions, as a thin wrapper around the lambda. Is there a better solution?

Thanks, Alex