> Files are not growing with each save ...
That rules out recursive Text Inset imports (that import themselves). Your problem is apt to "merely" be instances of copy-into-document.
If you need to hunt, save the document as MIF and open it with a plain text editor.
All imports contain the tag:
<ImportObject
By-Reference Imports look like (EPS example):
<ImportObject
...
<ImportObFileDI `<u\><u\><c\>path<c\>filename.eps'>
<ImportObFile `../../path/filename.eps'>
Copy-Into Imports lack those <ImportOB... tags, and look like (EPS and TIF examples):
<ImportObject
<Unique 3288853>
<Fill 7>
<Separation 0>
<ObColor `Black'>
<RunaroundGap 6.0 pt>
<RunaroundType Contour>
=TIFF
<ImportObject
<Unique 3288835>
<Fill 7>
<RunaroundGap 6.0 pt>
<RunaroundType Contour>
=EPSI
followed by metadata and thousands of lines of hex code.
Clue: the original file name of the imported object can often be found in the meta, but the presentation varies with file type.
Alas, as you can see with
select object in frame
Graphics > Object Properties,
Frame pretty much forgets what an import was, and where it came from, when (*) Copy Into is used. Big problem for information stewardship, not to mention capacity planning.
In FrameMaker 11 you can also use the the Inset pod to check which imported image is copied into the document.
Open the Inset pod with View | Pods | Insets.
Referenced images show the path.
Images which are copied into your document show "No File".
Much easier than reading the MIF file tags.