How to filter FAYT on expanded folders?

If I use FAYT on several expanded folders, I can find every file with a specific name. Now I want to be able to press a button or command, and then filter/isolate those found files only. How can I?

I am not interested in having Windows Search index everything, plus it takes forever on networked drives. I also don't want results from all other subfolders or adjacent folders. A simple isolate on the already found files in the expanded folders only is what is desired. Can it be done?

Have you tried sending them to a collection?

Nope. How to do that? I cannot right click on the files, because that loses the selection.

The basic command is

Copy CREATEFOLDER=coll://MyNewColl

You can also drag the files into a collection.

This shouldn't happen. If you check Preferences / Miscellaneous / Windows Integration / Add File Collections list to the Send To menu you can send the files to a collection via the context menu:

When I do FAYT, and then I right click any of the found files, all the other found files lose their markings.
So they're not selected. Is there a specific command to make them selected?

The default is Ctrl-A.

That selects all files in a folder.
I think you fundamentally misunderstand what I'm trying to accomplish and what is going on.

Are you using FAYT in simple Find mode ?
That would be by typing directly the word you're searching in displayed files and folders.
If so, I don't know how to achieve what you want because the files are not really selected. Matching files/folders just appear with the word you types highlighted and you can switch from one to the next with F3.

If you're using the Filter bar (meaning you start by typing * by default), then what @lxp describes is working because files are filtered, and you can now go back to the file display and do CTRL-A to select them all.
But that method does not select files in expanded subfolders.

What seems to work is the Selection mode of the FAYT. By default, you activate it by starting to type : then typing the word you want to match. Doing so, the matching files include the ones in expanded subfolders and they are selected. So, you can then right-click them to do whatever you want, or use a command like the one given by @lxp to put them in a collection, or copy them to clipboard with CTRL-C, or create a button or a script that acts on selected files, ...

Thank you!
Using : does work to select the files in the nested folders and they can be added to a collection. I also tried filterbar previously, which as you said unfortunately doesn't work on nested/expanded folders.