Thank you to all for the kind and informative responses.

We had initially bought a different itinerary but ended up with this itinerary due to an airline schedule change around December 2021. We agreed to it at the time, because a 2 hour connection seemed okay in December of 2021. Things have changed in air travel obviously, and now it looks like having more time would be beneficial.

I was hopeful that I could make this change because the BNA-EWR flight I hold a reservation for is more expensive than the one I proposed transitioning into.

Thanks for the idea about SDC. I will keep that in mind and may do it. Standby-- maybe we'll do it, but obviously we then end up in coach (not the end of the world of course).

I have considered buying one way tickets on the BNA-EWR segment that I'd like, but if I do this, can I cancel the original BNA-EWR leg without losing the EWR-SNN leg?

Thanks to all