Try this: instead of using a Forwarding rule in Groupwise, use a "Delegate" rule. Forwarding strips out attachments, but delegating leaves them.
The only way for emails forwarded (or delegated) from Groupwise to show the original sender in the From field is by changing a default setting on the GW mail server. My IT department said "Hell No" when I asked them about making this change. Eventually, I convinced them to add me to the BES.
The Blackberry site has a boatload of articles about Groupwise and its many problems. Tell your wife to read a few if she wants a laugh