You could do it using a puk welding machine.. I have one ideal for this type of job. It is welding through 10x optics with a needle electrode. Expensive kit and a steep learning curve. An even better way is laser welding but I do not have a laser welding unit and your job might not fit in the laser unit. I live in the UK. I would find a jeweller or silversmith in your area that is using a puk welding unit near you should be straight forward. I better pic would help.
https://www.bettsmetalsales.com/jewe...uk-welding/puk