Shell Programming and Scripting

I'd like to remove (do a pattern or precise replacement - this I can handle in SED using Regex )
---AFTER THE 1ST Occurrence ( i.e. on the 2nd occurrence - from the 2nd to fourth occurance ) of a specific string : type 1
-- After the 1st occurrence of 1 string1 till the 1st occurrence of string2 not counting the latter.

e.g.

Code:

Begin Transaction ;
She sells
sea shells 
by 
the 
sea shore
End Transaction ;

Begin Transaction ;
For if she sells sea-shells on the sea-shore
 Then I'm sure she sells sea-shore shells.
End transaction ;


Begin Transaction ;
The shells sh
e sells a
re sea-sh
ells, I'm s
ure.

/* Notice How I made the above English incoherent by putting newline breaking words, those newline need to go */
End Transaction ;

Code:

replace function () 
Blah

- How do I go about knocking of the newline char between Last Begin and End transaction pair
Program Thought : Go find the 3rd Begin transaction statement and knock off the newline until the 1st end transaction statement

Moderator's Comments:

Please use [code] and [/code] tags when posting code, data or logs etc. to preserve formatting and enhance readability, thanks.