Android : Handling parallel backstack Fragments for an Activity

I have a layout designed as

_________________________________
|Option A|                      |
|________|                      |
|Option B|                      |
|________|      Fragment X      |
|Option C|          of          |
|________|      Option i        |
|Option D| (i is (A,B,C or D))  |
|________|______________________|

Option A --> A1 fragment -->A2 fragment--->A3 fragment

Option B --> B1 fragment -->B2 fragment--->B3 fragment

Option C --> C1 fragment -->C2 fragment--->C3 fragment

Option D --> D1 fragment -->D2 fragment--->D3 fragment

These all fragments are in one Activity.

Clicking on option A,B,C,D opens fragment A1,B1,C1,D1 respectively. From those fragments I can navigate internally till level 2/3/back (levels here are representative of depth,nothing much technical). However option A,B,C and D can still be clicked.

WHAT I HAVE: User is in Fragment B2. He clicks on Option D, D1 comes up he can navigate till D3. Now,when user clicks on option B he goes to B1 fragment.

WHAT I WANT: User is in Fragment B2. He clicks on Option D, and navigates till D3. When user clicks on option B he should go to B2 (rather than B1).

WHERE AM I STUCK: How to get the state B2 and use it so that I also have backStack compatibility.

WHAT I THINK: I think I should have a separate fragment manager for each option. But I am unable to set the fragment(B2 in our case).