Planning Function & Characteristics Relationship

Hi Experts,

I need a help in some basics of Planning functions.

We have a Planning cube on which several aggregation level built. Among them only one aggregation level (say example ALVL1)has an additional InfoObject (Say example CHSBS)which is used as changeable object in the Planning function created over ALVL1.

Since the infoObject CHSBS not included in other aggregatoin levels we have written a Characteristics relationship to derive the value. Now the Planning function on ALVL1 is not running as the InfoObject is being changed by both Planning function and Characteristics Relationship.

My questions is as below:

Is there any possibility that we can change value of an InfoObject by both Planning function and Characteristics Relationship ?

or

Is there any document which explains changeability of InfoObject by both Planning function and Characteristics Relationship is not possible ?

Thanks,

Gopi R