Hi Ash
I don't have Winpath but I have this working in a Telepath System. It would all depend on how the data transfer is taking place from ICE to Winpath. If it's via an HL7 type interface, you should be able to get a specification from the supplier that will tell you what data goes where in the message.
The way mine works is via rules in ICE that ask for the Product required, number required, date and time required. We don't have it live as yet but the testing seems to have worked well with all the fields in the lab system populated as expected.
What would happen if the number of units was amended, I don't know, I'll test it and find out. My suspicion is that if the request is still outstanding on the lab queue it would just overwrite. Practically speaking, we wouldn't want people to be amending electronic transfusion requests adhoc anyway, if there was a need for a change, out transfusion manager would want a phone call first.