Question: Existing filters as components?

YES, you can use combine and mix different filters together

The Snippets Category in the FF Library, is exactly for this topic, to use them as a group of components to be used on other filters.

To be able to mix two filters, consider them as like a group of components, so

1 - Double click the filter you want to use so you open it in the Filter Editor

2 - Sel ect and copy all the components (or only the ones you need) until just before the Result and then close this filter

3 - Double click on the filter you want to use the copied components, and when in the filter editor, find an empty space and paste it on the filter you want to use.

If wanted You can put a note near these copied components to know what they are and they do, or where they come from.

If you use other filters fr om the FF library, and you want then after submit this filter to the library it would be good and great if you could take note of who made that filter and then in the description give thanks to the author, or authors, of the filter or filters you have used.

If you are using a filter that has a Surface or PBR result component will maybe more difficult to use as the result depends on the combination of the results of different components, so maybe this could be the destiny of other filter instead of copying this one.

It is recommended that you read the FF wiki to know about this