Is it possible to include relationship sources in Family Search in the comparison between Family Search and Roots Finder?
That seems reasonable. It’s may be easier if the source is just added to the one individual though, not both. If you wanted a relationship source added to both individuals, it may need to be added to the other individual as a separate source. Is that ok? It’s also possible to add it to both individuals, but it will be more involved.
That’s OK. Keep it simple 
It will just be helpful to be able to see that it is there.
With thanks
Marlene