Agent Protocol Question

I wouldn't. I would just save the new manuscript with the new chapters as a separate file specific for that agent. The previous agents probably have enough submissions on their plates as it is and wouldn't really like having someone submit a duplicate sample. It's just one more thing to keep track of. And you never know, they may love it as it is.

Spiny's right. Don't try to second guess the other agents. You might be surprised that one of them likes your original version just the way it is. But if the feedback turns out to be similar on the same issues, then it would be time to rethink the project and revise. Good luck.

Agreed. If they don't ask for anything, they're not interested, and contacting them unsolicited with improvements just makes you look desperate, amateurish, or both.

I agree with the other folks, leave well enough alone. I've had completely opposite reactions to the same manuscript, fwiw. Now, if more than one or two agents weigh in with the same feedback, that might be another story, but you still should question the strategic benefit of contacting those with partials, as it might seem like you hadn't sent them your best work. You could instead try querying a new batch of agents with the revised partial. good luck with the revisions!

Make the changes and resend to the one who showed interest.

If and when the others should come back you can ditch the old version and try another round with different agents with the new one.

All of which is cancelled should the first agent accept your changed version.

This happens all the time. Your work should keep morphing as you send it out. Just make sure you know which agent got which new, improved version!

If one gets back to you expressing interest in an old version he or she won't mind that you've improved things. They've seen it before.

Good luck!