Hi, juzzvinay!
Give a look at this file:
https://dl.dropboxusercontent.com/u/60558749/Merge_Stack Multiple Named Ranges (Across Multiple Worksheets) in a Master Sheet (for juzzvinay at chandoo.org).xlsx
It uses 3 dynamic named ranges for each worksheet Hoja1/2/3:
Table1: =DESREF(Hoja1!$A$2;;;CONTARA(Hoja1!$A:$A)-1;CONTARA(Hoja1!$1:$1)) -----> in english: =OFFSET(Hoja1!$A$2,,,COUNTA(Hoja1!$A:$A)-1,COUNTA(Hoja1!$1:$1))
Table2/3: idem for Hoja2/3
In worksheet Hoja0, summary, this is the only formula:
A2: =SI(FILA()-1<=FILAS(Table1);INDICE(Table1;FILA()-1;COLUMNA());SI(FILA()-1<=FILAS(Table1)+FILAS(Table2);INDICE(Table2;FILA()-1-FILAS(Table1);COLUMNA());SI(FILA()-1<=FILAS(Table1)+FILAS(Table2)+FILAS(Table3);INDICE(Table3;FILA()-1-FILAS(Table1)-FILAS(Table2);COLUMNA());""))) -----> in english: =IF(ROW()-1<=ROWS(Table1),INDEX(Table1,ROW()-1,COLUMN()),IF(ROW()-1<=ROWS(Table1)+ROWS(Table2),INDEX(Table2,ROW()-1-ROWS(Table1),COLUMN()),IF(ROW()-1<=ROWS(Table1)+ROWS(Table2)+ROWS(Table3),INDEX(Table3,ROW()-1-ROWS(Table1)-ROWS(Table2),COLUMN()),"")))
Copy across thru column C and down as required, i.e., until the 1st blank gets displayed (in the example light orange background indicates up to which row the formulas have been copied).
Adapt this method to fit in your actual workbook.
Regards!