Imagine getting double-teamed by your wife and her mom. When your bride goes out for the evening the mother-in-law could stop by to mind you... and bring that spiked cage with her.
The funny thing is that it is quite difficult for two girls to 'double-team' chastity. A guy is either locked or not locked ... you can't get a double-dose of chastity like you can get a double-dose of cane-strokes from two cruel women. I have actually seen chastity caps where two girls have a key to the chastity device ... but that makes it MORE likely the guy will get out! I've tried ideas like a multi-locked safe with the guy's key in it, so that ALL the keyholders have to agree before the guy gets unlocked, but it all get a bit complicated.
They could play 'good cop/bad cop'. Wife 'really' wants to unlock you but says Mom won't allow it. Mom claims that wife almost had her convinced but she decided against it at the last mlnute. Nice form of psychological torment.