Ku Med only allowing care in their system?

In Missouri/ Kansas.

Trying to get booked in with an ob for high risk pregnancy as well as for imaging for suspected cancer (don't recommend both at once).

My Dr office is part of the ku med system. They will not allow me to have the referral/ requisition for either in order to go somewhere else that's more cost effective, like diagnostic imaging or university physicians women's center. It is not a question of insurance coverage.

They are saying I must complete all of the required testing and appointments with their system. Ie:

For the cancer screening, I must have an appointment with their "nurse navigator" at a hefty price to confirm the need for imaging, even though the imaging is ordered already by my dr and pre-authorized already by my insurance, then I have to have all of the imaging together at their imaging center.

For the ob referral, they've said I have to go to a ku med urgent care to have the pregnancy confirmed, and cannot go anywhere else. Then I am only able to see a ku med ob and they will not refer me to any other system, even if another ob is a better fit for my condition.

Is this legal? Normal? I thought I had a right to take my testing orders wherever I preferred and choose my own doctors, as long as they have availability. Can ku med really refuse to see me without all of the extra appointments and without doing all testing in their system?