I'm not quite sure of the manual process you are describing - but editing the shape directly is something I've avoided.
To add a visual separation between text flowing around an embedded frame (image or anything else) I have used two approaches:
- Create an empty frame that is slightly larger than the embedded frame, align centre, group the two objects, setting the flow on the group (uggh)
- Add a border to the image frame, set the colour to white .. or whatever works with your background, limited width but really easy and amenable to scripting!
#1 is a hack but can do anything .. and can just about be scripted if you need it to be repeatable / automated
#2 is the easiest both in user terms and scripting - but is limited to same width on all sides and also limited in width. Add your image, select the frame and run this (update the name to match your frame):
# text flow mode 2 is bounding box
setTextFlowMode("nameOfFrame", 2)
# add a line to your frame (shape, image text .. whatever)
# "White" needs to be in your colour palette
setLineWidth(6, "nameOfFrame")
setLineColor("White", "nameOfFrame")
cheers
Rob