Scenarios of copying variables

This post is an extention of this this thread.

In this case scenario is I'd like to copy the container B into container A but for the A cointeners' subproperties do:

1. if A subproperty exists, but the subproperty exists in B container and their values are equal - do nothing
2. if A subproperty exists, but the subproperty exists in B container and their values are not equal - retain value held by A (destination)
3. if A subproperty doesn't exist but the subproperty exist in B container - create subproperty from container B in container A along with B's subproperty value.

Is it possible wthout iterating subproperties over in the subsequence?