adjustments in spine strengthening series

Hello,
I have a student who has been coming about 3 times per week for the past two months. She came with some very severe issues in her lower spine. While I dont know the very specifics of her injury she has visible scars on her spine and little to no flexion of her low back. In any of the compression postures (standing and separate leg forehead to knee and rabbit) she works actively to round her spine- I can see her using her tummy muscles as much as possible- but it appears that her spine just wont budge down there.

She approached me tonight after class to ask about alternatives for the spine strengthening series, sighting tremendous pain in her lower back in all postures. I suggested she try a bridge and she was able to lift her hips off the floor with no problem. I was wondering if you could help with some other alternatives during this portion of class. I am aware that there are adjustments for pregnant women (but i dont know what they are)and perhaps she could use some of these.

Thanks very much!