Q: can we have two devices on the same apple id signed in and transmitting at the same time?

Apple IDs are designed to be used by one person at a time. You can have multiple devices attached to the same ID but the expectation is that they are all being used by the same person. You're experiencing just one of the problems inherent in trying to share an Apple ID.

You should each have your own Apple ID. You can use Family Sharing to share data and content.

There has been a past discussion on this. Here you will find the device limit for 1 Apple ID.

There is a limit of how many apple devices I can connect my Apple ID to the App Store?

Cheers!!