git - Push to all branch but only have same code? with follow up question

Question

Did git can push to all branch but Only have same code? I mean if i have 3 branch like ver_light, ver_medium, and ver_heavy.

= ver_light
\controller\a
\controller\b

= ver_medium
\controller\a
\controller\b
\controller\c
\controller\d

Fisrt, i change ver_medium in controller A and C. How i do in git without git push controller c in ver_light branch?

Second, this example only 1 or 2 file. How about more than 100+ file? Do i needed select or pickup i need change to ver_light branch?

Third, did git have setup file like : oh, this code only can be push to certain branch and this code can be pushed to all branch ?

Sorry for my bad english. I got C+ but it wont stop to asking.