Sorting with merged cells

Dear Experts,

Need your help in sorting when multiple cells are merged.

Trying to explain exact problem below.

1. Column A - Document Name (rows merged as same document assigned to multiple persons)
2. Column B - Document No. (rows merged as same document assigned to multiple persons)
3. Column C - Responsibility which is assigned to multiple people and all responsible person names written in separate row.
Now when I sort with column A only one person name get sorted rather showing all responsible persons name.
Similarly when I sort using Column B also.

Note: If I capture document name and no in all respective rows, I am able to sort. But as have to handle much more no. of documents, my excel becomes hotchpotch with same name and no. written at lot of places.