Combine data in two cell into one

Hello,

Similar thread match with my problem should be solved on somewhere in the forum.
But i can't find it.

I want to combine two cells single cell, it's like permutation/combination i am not sure.
example:

cell1 cell2 cell3

A 1 A1
B 1,2 B1,B2

Is it any efficient formula? i am think using subtitute function,

=CELL1&SUBSTITUTE(CELL2,",",","&CELL1) but not work well for data more than one in cell1 and cell2

please check attached file.

Thank you.