If you don't mind using a filter and deleting some columns, then I would suggest this:
=IF(ISBLANK(A2),CONCATENATE(B1,";",C2),B1)
Assuming that the first line is on row 1, then copied down.
You then need to copy/paste values in place on this column to remove the formulas.
Last, insert a filter and delete all rows with blanks in column A.