SerializedProperty and restoring reference after change

How do I restore reference when creating and changing prefabs:

asset: asset-(geo1,geo2)
where (geo1, geo2) represent two meshes parented to asset and asset the root node of this asset (a maya file)
prefab : root-GEO-asset-(geo1,geo2)
root is the top node, GEO is parented to it and asset-... parented to GEO
Script is connected to root and contains a variable called target
target is referencing geo1

when I replace asset under GEO the reference of target to geo1 is broken

how do I keep track of this connection and how do I restore it ?