Thank you everyone for the responses; super helpful.
@ton37, I believe what you're doing is using the computer screens as a replacement to the paper, and you load up your registrations distinctly? In other words, the two are not linked?
@muddy - thank you for the guidance. I haven't played around with that yet, because it looks quite fiddly. I get frustrated with the fiddly and want to play! Is it correct that you have the control and can link what you want? In other words, you are deciding what sheet music to put and what registrations to link it to? So while fiddly, you end up with exactly what you want and it can grow as your collection grows?
@AI ram - thank you. I'm not at all set on Mobilesheets, it was the only one I'd seen that can link sheet music in an electronic format to the registrations. Is songbook+ a closed system? It appears that the adding of the sheet music and linking to registrations is done by the company selling the product? From the videos I saw, they have about 200 songs. It also seems that it is their selections of registrations etc? So on the one hand it is easy because less fiddly, less for me to setup, they've done more of the work. On the other hand, it doesn't expand to whatever I want and less customization? Is that right?
I fully appreciate that every avenue has time investment to get it to work, fiddly bits, etc. I'm just trying to do some homework on which is best suited for my particular desires, knowing those may well be different than others.
Again, I'm really glad I've discovered this forum - so much helpful information.