Combine rows

I don't understand. Do you mean like this?

	A	B	C	D
1	A1	B1		Combined
2	XXXXX	XXXX		XXXXX
3	XXXXX			XXXXX
4	XXXXX			XXXX
5	XXXX			XXXXX
6	XXXXX			XXXXX
7	XXXXX			XXXXX
8	XXXXX			XXXXX
9	XXXXX			XXXXX
10	XXXXX			XXXXX
11	XXXXX
12	XXXXX	XXXX

A1 = 1111 B1 = 2222
A2 = 2323 B2 = blank

then B3= A1&" "&A2
and so on
if B2 = blank then B3 = A2

and so on from all A$ & B$

sorry attachment is not available on my browser i dont know why