No and yes.
No: if there's no specific API for it, then there's no easy way.
Yes: You can build a follower-tree (A follows B, B follows C, C follows
D, etc) from the original tweep, but that may take a lot of time
depending on the amount of retweets, and should probably only be used
for research purposes.
Tom
I think that it is safe to assume that if user B follows C but not D, that he/she will retweet C and not D. However, this is not always 100% accurate. If an user follows both C and D, he/she will have retweeted the first one who retweeted it - the user does not get the second one in the timeline.
Tom
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