Howdy. You can use a hidden column (C) with concatenation on Data worksheet with this formula:
=A2&B2
Then name the range (using dynamic named range formula)- MyLookup
=OFFSET(Data!$A:$1,0,0,COUNTA(Data!$A:$A),1)
Then you can name other ranges off this using this formula; for instance column D, named range could be RngD,
=OFFSET(MyLookup,0,1)
etc.
Then do a concatenation on the Summary worksheet as well, and then do a lookup formula based on that to the MyLookup named range.
Hope this points you in the right direction. If you want mor,e perhaps post a sample.