@Frank Thanks for your reply.
Our adapter board has a TCA9546 1-to-4 I2C switch that extends the single I2C bus from VIM3 to access the 2 cameras. We use the PCA954x driver to get the extended I2C into Linux. So, I think we are on track on the I2C side.
Our biggest concern is if the MIPI interface driver support 2 camera streams and, if it does, how to configure the MIPI interface and drivers to present them as devices under /dev.
As I understand it the hardware supports 2 cameras (our cameras are low resolution cameras) so this is more a question of if the software support is in place or if we need to plan for adding the support or find some other solution.