@Praveen – the first question you have to answer to yourself is:
is there a general prescribe where to anchor exactly a single text frame in the main story?
If you cannot say that in a general, logical way, you cannot automate this task.
Or you have to programme a lot of exceptions, that it would be easier to do it manually.
For InDesign CS5.5 and above it is very easy to anchor a text frame using the UI with two clicks per instance. Scripting those is a more complex task.
1. You have to identify separate text frames (you can only anchor single, non-threaded ones!).
2. Perhaps you have to identify a geometrical relation between the single text frame and the main story in form of a single insertion point at the beginning or end of a paragraph…).
3. And you have to define some properties for the anchor behaviour of the stray text frame you want to anchor.
How many stray text frames do you have?
How many documents where you want to anchor those?
Describe the projected time for the task if done in the UI…
Is it reliable using a script at all?
Taking into account that writing (20%) and testing (80%) a script for this task would take some hours to perhaps a day… Plus the time for analyzing the original documents (special cases may be a hurdle one cannot overcome).
Uwe