Grandmoms are sometimes from an era when surgery was to be avoided at all cost and when they didn't have the advance techniques that they have today. What is she afraid of? Is it your child's surgery or is this her pattern of dealing with health care? I agree to show her the xrays. It would be great if PT would cure it and as a mom, of course you want the best for your child and would not want your child to have surgery if it were not needed.
You are the mom and the guardian for your child and you're been to the appointments and weighed the pros and cons with the doctor. Not having the surgery can lead to long term problems and further disability in children. So, do all of the rational things that you probably have already done w/ your mom and talk to your daughter as mentioned above [that was a great mom-daughter discussion that a prev person had]. Finally, have coffee w/ your mom and tell her that for medical reasons and your child's long term health, your daughter will have the surgery. That it would be so much easier on her grandaughter if EVERYONE was supportive, and if she can't be supportive, then just smile and give a hug to her grandaughter.
Good luck. What a tough place to be in, but you have the right instinct.
Susan
Adult Onset Degen Scoliosis @65, 25* T & 36* L w/ 11.2 cm coronal balance; T kyphosis 90*; Sev disc degen T & L stenosis
2013: T3- S1 Fusion w/ ALIF L4-S1/XLIF L2-4, PSF T4-S1 2 surgeries
2014: Hernia @ ALIF repaired; Emergency screw removal SCI T4,5 sec to PJK
2015: Rev Broken Bil T & L rods and no fusion: 2 revision surgeries; hardware P. Acnes infection
2016: Ant/Lat Lumbar diskectomy w/ 4 cages + BMP + harvested bone
2018: Removal L4,5 screw
2021: Removal T1 screw & rod