Difficulties with wearing a device? discussion

Hi, I have two silicon Bird Locked chastity devices. One has a 40mm hole and the other a 45mm one. When I wear the 45mm device for extended times, one of my testicles slips through first, followed by both, allowing me to remove it while still locked. The 40mm model keeps everything in place but gets uncomfortable after some time as you might guess, so I have to take it off. Can I stretch the silicon on the 40mm device a few millimeters up to around 42-43mm? Or does just wearing it naturally stretch it out too? Ideally without breaking it in the process. Thanks for your help. Best, Tom