First of all, there is no such concept as passing values between class modules. Class modules are (essentially) templates used for creating instances of the class described within them.
These instantiations of classes (called objects) have values, but the modules that describe how these instances should be created do not.
In the class module, create an exposed variable of the type of the other class that this class must work with.
Public TheOther As clsTheOther
Create a method to do your manipulating.
Public Sub MakeChange()
TheOther.ItsProperty = Me.MyProperty
Then make an instance of both classes, set the public variable of the class I've shown the code of here to be a reference to the object that needs to be changed, then call the method.
. . .
Dim objWorker As New clsWorker
Dim objWorked As New clsRecipient
' Set a reference. (There are now 2 references to the same object.)
Set objWorker.TheOther = objWorked
objWorker.MakeChange ' Do the work
Set objWorker.TheOther = Nothing ' Release the reference
. . .
objWorked will now have the value that you set it up to receive, having come from the value you set up to send in objWorker.