Re-creating old radio episode of Fibber McGee and Molly- need to manually create the SOUND of (for live audience to see) 7 mirrors breaking in succession - safely. Thanks for your suggestions.
I really think your best plan here is to break seven panes of glass (or in reality break quite a few, so you can get various recordings)
Depending on what acoustics you need, the best breaking glass sounds I have come across were in an old concrete-floored warehouse, and the breaking action was a drop from waist height. The glass we tried varied from 1ft x 1ft up to about 3ft x 1ft, but the best ones were the smaller ones.
Try to set up at least two mics, one directional mic pointed at the point of impact, and one omni (or directional pointed at a nearby wall or corner) as the echoes can be an essential part of the mix.
You'll want to try different angles - you get very different noises depending on how they land.
Steel-toecap work boots, goggles and work overalls are essential.