Odd Behaviour using User Variables to select members in Planning form

Question

I have a form to enter budget adjustments and another form to review the effects of those adjustments at a parent Entity level.
For each area of the business there are obviously different adjustment and parent levels required in the form.
In summary I can drive a form from a User Variable using the functions (Children, IChildren, ILvl0Descendants, Descendants and IDescendants) but trying to use other options results in unexpected behaviour.
For example with the following structure:
Entity
-Total Cost Centre
--Group A
---SubGroupA1
---SubGroupA2
---SubGroupA3
---GroupA-Adj
----GroupA-AdjX
-----AdjEntityA1
-----AdjEntityA2
--Group B
---SubGroupB1
---SubGroupB2
---SubGroupB3
---GroupB-Adj
----GroupB-AdjX
-----AdjEntityB1
-----AdjEntityB2
For the adjustment entry form the users would want to see AdjEntityA1 and AdjEntityA2 if they are in business group A.
For the review form they would like to see Group A and its children.
I am trying to avoid writing multiple forms for each business user (largely because the number of groups can vary dramatically). I can't really use generations to drive the selections as whilst the business has effectively levelled the hierarchy business units can be working at different levels of this hierarchy.
I want to offer a couple of options to the business. One will be to define a form that pulls all of the relevant entities into the form and relies on security to restrict the values displayed to the user. The second option would be to utilise User Variables to drive selections. It is the second option I am struggling with.
If we consider a user working in Group A, I think I can see a formulaic way to select the various combinations of Entities if I set the user variable to be GroupA-Adj.
I can define a data form that sets Entity to the L0Descendants of say GroupA-Adj and this is fine.
When I try to define a review form that selects the Isiblings and Parent of GroupA-Adj I hit a problem.
It seems that Children, IChildren, ILvl0Descendants, Descendants and IDescendants works as I would expect.
Using IAncestors and IParents return just the User Variable setting (i.e. just the 'I' part, not the parents or Ancestors).
Siblings, Isiblings, Parents, Ancestors all result in an error message because not all dimensions are represented in the form.
This prevents me using a User Variable to build the review form in which I would like to display the siblings and parent of the entity GroupA-Adj.
Anyone got any ideas?

Answer 1

I would love to see the ability to select EDA's from Planning Forms, it would definately make life a little easier.
As CL says, attributes are great at filtering forms and BR's, their only drawback is that you can only use them on sparse dimensional members.
To get round this problem i've relied on security to filter out the accounts i do not need to see in the forms for the specific users, and kept the form selection on @IDESCENDANTS(Account_Parent).
If you wish to filter on the Period dimension and this is a dense dimension, can you not get round the problem with rollups and, for example, @DESCENDANTS(Q1) to only return 3 months in the form, it really depends on your outline structure.