I'm trying to use the formula in B1 and concat b4:b12 if the value in A4:a12
is equal to A1 (the number 1) - like the result shown below. Is it possible ??

A B
1 J2,Q2,K1,C7
2
Unit Group
1 J2
1 Q2
1 K1
2 S8
2 I2
2 N2
1 C7
2 V3