This is a bit tricky. I can tell you the logic. The problem mentioned hapeens only in web.
when you use file upload control in wenb it shows as browse button. beside this you create one more button and name it upload.Then
for every upload you should have two hidden fields. One hidden field will store the name of currently selected file using browse button, once upload button is clicked the attachement is saved in the document and the name of currently saved file comes in the second hidden field. thus when some more file is attached then current selected file names comes in first hidden field and when saved the name is appended in the second hidden field. this you have to implement it in the upload button logic.
similarly you can do for two more uploads. once the document is opened in client it shows at the bottom, here you have to write a script in post open event of the form where you will get the attachment names in the second hidden fields for every upload and put in the corresponding rich text fields.
I have done this. and it works perfectly. Try this. If you need the code or example I can send you the ntf file which will help you . I am seeing your question today and answering this. But same question I had asked earlier in this forum, but later to your question date. Then I found the solution and I mentioned it earlier too.