1. In a computer system comprising a parent and a child development environment, said parent and child environments having a first and a second delta hierarchy representing a source module and changes to said source module individually known to said parent and child environments respectively, a method for merging said first and second delta hierarchies together that preserves all delta relationships of said changes individually known to said parent and child environments without the need for computer assisted tracking, said method comprising the steps of: (a) storing deltas in a first and a second list of deltas and storing descriptive entries corresponding to said deltas in a first and second table of descriptive entries of said first and second delta hierarchies; (b) initializing a first and a second work list and a first and a second work table to equal said first and second list of deltas and first and said second table of descriptive entries of said first and second delta hierarchies respectively, said first and second lists of deltas being chronologically identified within a first and a second development environments in identical manners, and said first and second table of descriptive entries being time ordered and correspondingly describing said first and second lists of deltas respectively; (c) initializing an output table, an output list, a first and a second two way associative array corresponding to said first and second work tables to empty, for sequentially receiving modified non-duplicate descriptive entries of said first and second work tables, modified non-duplicate deltas of said first and second lists of deltas, and cross reference entries cross referencing descriptive entries of said first and second work tables and said output table to each other; (d) retrieving descriptive entries and their corresponding deltas from said first and second work tables and said first and second work lists, outputting a two way cross reference entry to the corresponding one of said first and second two way associative arrays for each descriptive entry which has been retrieved, as the descriptive entry and its corresponding delta are retrieved, cross referencing said descriptive entry which has been retrieved to the next descriptive entry of said output table, said step of retrieving being performed one descriptive entry and its corresponding delta at a time, in a predetermined least recent entry manner, until all descriptive entries and their corresponding deltas have been retrieved from said first and second work tables and said first and second work deltas; (e) discarding each descriptive entry which has been retrieved and its corresponding delta, as its two way cross reference entry is output, if the descriptive entry which has been retrieved is a duplicate of a second descriptive entry which has been retrieved in the other work table; (f) modifying each said descriptive entry which has been retrieved and its corresponding delta not discarded, after its discard or not discard determination is made, outputting each of said descriptive entries which have been retrieved and modified and its corresponding modified delta into said output table and said output list respectively, as the modifications are made, said step of modifying being performed in accordance to whether a new branch is to be created in the merged hierarchy for the corresponding delta of the descriptive entry which has been retrieved and not discarded, and the number of descriptive entries which have been retrieved having been output to the output table so far, and furthermore utilizing said cross reference entries.