When building an Essbase dimension build file, 99% of the time, I will build it using a Parent / Child relationship. I feel its the easiest to maintain and shared members are added automatically. Here's a simple example for the Scenario dimension:
Scenario|Actual|+|
Scenario|Budget|~|
Scenario|Forecast|~|
Scenario|Revised Forecast|~|
In case you were wondering what the + and ~ mean or need more properties, here's a good list for you:
Essbase Member Properties for Aggregate Storage Database
% Set consolidation to express as a percentage of current total.
* Set consolidation to multiply by the current total
+ Set consolidation to add to the current total