to join several programs

[lfjil]

Dear gurus
I'm facing to join C language programs for diferent apliances connected to a cypress microcontroller, as display, 2 I2C sensors, 2 ADC, and 3 PWM out, so each program has its headers or includes, its definitions, functions and program.  So when I have to join all that, it seems more as an spaghethi, and have to verify that the variables names match, and the general algorithm stay working as planned. 
Which would be the best utilities or tools to make this as easy as possible in Code blocks?
I know some of C language but I'm no proficient yet.  I preffer to avoid tricks as supercharged operators and rare things
I thought about the folding characterstic of F12, but maybe there is something better to mix programs.

Sincerly
Luis