This is regarding creating imaginary trains. My suggestion is to give an option to tag an imaginary train as a RSA of another imaginary train of ours. As of now, we can tag a real train as a RSA of an imaginary train, by inserting the real train number. Anyway all the imaginary trains have unique train numbers. As of now we are able to tag the imaginary return train as a return journey of another Imaginary train, by inserting the unique imaginary train number. Same way in RSA, we should be able to tag our other Imaginary trains as a RSA train, with link address/imaginary train number.