How to slip a file into a folder downloaded via μTorrent?

Question

bittorrent

μTorrent downloads a folder with files.
It downloads slowly, because there are few full sources, so the distribution is slow.
One of the downloads, however, I already have, having previously been downloaded from another source.
Is there a way to put this file in the mutorrent in the download folder - firstly, so as not to waste time re-downloading it, which is already slow, and secondly, immediately start distributing this file and thereby help other file sharing participants?
If yes, what is this method?
How reliable is this method? (Will µTorrent check the slipped file against the hash from the torrent to make sure that the file does not contain bad pieces and that it is serving exactly what is needed?)

Answer 1

Stop the download, copy the file and then update the hash (RMB on this torrent and at the bottom of the menu there is this item) and start again.