Proxy for com port. How to organize?

Question

Serial port

There is a task to read data from the com port on the computer and send it a little bit to the same port. Or to another virtual port. It is necessary to clean the data from the port from garbage and send it to the port. Because the program does not know how to do it. Now I see only this way:
- my program reads the real port, parses the data, cleans it from garbage and sends it to the virtual port. This port is connected to another virtual port (for example, via com0com), from where the main program will read the already corrected data. But maybe there is an easier way?