Multiple if statements, trying to add logic

[#1]

If A1 Date >= 1 and A2 date >= 1 then do one of the following

If A1 date <= A2 date show A1 date-setup, else show A2 date-setup date, else

If A1 date >= 1 then A1 date-setup date, else

If A2 date >=1 show A2 Date-setup date, this will show the data date – setup date

            if( (len(trim([First A1 Date]))>=1 and len(trim([A2 Date]))>=1),
                     if( [First A1 Date] <= [A2 Date], ( [First A1 Date]-[Setup Date] ), ( [A2 Date]-[Setup Date] ) ),             
                     if( len(trim([First A1 Date])) >=1, ( [A1 Date]-[Setup Date]),
                     if(len(trim([A2 Date]))>=1, ( [A2 Date]-[Setup Date] ), ( [Data Date]-[Setup Date] ) ) ) ) as [Age_Setup]  ,

I know want to add in the B1 Date and B2 date and give it the exact same logic as A1 and A2  Here is what I have done so far                                                                                        

if( (len(trim([First A1 Date]))>=1 or len(trim(First B1 Date]))>=1 and len(trim([A2 Date]))>=1 or len(trim([B2 Date]))>=1),
                     if( [First A1 Date] <= [A2 Date], ( [First A1 Date]-[Setup Date] ), ( [A2 Date]-[Setup Date] ) ),

                  if( [First B1 Date] <= [B2 Date], ( [First B1 Date]-[Setup Date] ), ( [B2 Date]-[Setup Date] ) ),
                    if( len(trim([First A1 Date])) >=1, ( [A1 Date]-[Setup Date]),

             if( len(trim([First B1 Date])) >=1, ( [B1 Date]-[Setup Date]),

  if(len(trim([A2 Date]))>=1, ( [A2 Date]-[Setup Date] ), ( [Data Date]-[Setup Date] ) ) ), if(len(trim([B2 Date]))>=1, ( [B2 Date]-[Setup Date] ), ( [Data Date]-[Setup Date] ) ) ),  ) as [Age_Setup]  ,

I am having issues with my brackets based on this logic.  The last bracket should encompass everything beginning with the first if statement