Fine silver is remarkably soft when fully annealed, so you should have no problems. Make a band that will just slip inside the ring and then swage it out into the concavity of the band. To do that, I'd probably make a small snarling iron with a ball end that about matches the curvature of the ring's concavity and use that to force the fine silver band into place, followed up by a thorough burnishing with a small ball burnisher. When it feels like the fine silver is fully mated to the ring, you can solder it in place with some "easy" solder and be done. You may not need to solder it at all.
David, Fine silver is
David,
Fine silver is remarkably soft when fully annealed, so you should have no problems. Make a band that will just slip inside the ring and then swage it out into the concavity of the band. To do that, I'd probably make a small snarling iron with a ball end that about matches the curvature of the ring's concavity and use that to force the fine silver band into place, followed up by a thorough burnishing with a small ball burnisher. When it feels like the fine silver is fully mated to the ring, you can solder it in place with some "easy" solder and be done. You may not need to solder it at all.
I hope this solves the customer's issue.
Rich