Chessbase transpositions

Hi.
Yesterday I was teaching a friend what I know on how to use chessbase and he asked me something that I myself often wondered which I am hereby asking you.
Is it possible to merge the databases in such a way that it is able to tell whether a given position occurs elsewhere in the merged file (or maybe even in the database itself) (through some transposition of moves) - and therefore refer to those lines in the variation tree?...if so... how?
If not, then maybe there is a way to copy lines (preferably trees). Is there? Any other method that would accomplish that task?

Thanks guys

I don't own the most recent version of Chessbase, but I remember on version 8.0 you were able to search database (or databases) by position. I also remember certain structural searches (for example any position with a Sicilian pawn structure regardless of which pieces were on the board).

@dRr0x0rZZ - What I need is for the software to recognize that the line mentioned already exists in the file. for example.... The position after e4 e5 Nf3 Nc6 Bb5 is a position after which black can reply with the most popular a6 or Nf6... Imagine you have a file in which you know the responses to each of these branches of the tree3 which can be thought of trees in themselves. Now that is the same position as i after e4 e5 Bb5 Nc6 Nf3. Now I don´t want to have to input all the moves that I have done in the other line for this particular position. I would like to copy and paste those options (Nf6 and a6) including sub variants, into this position or somehow make the software refer to that same branch on the file.

Thanks