Tricky Situation with fmil

A few weeks ago I met my FMIL for lunch to catch up and discuss some wedding things. (My Fiance and I have been together for 9.5 years so we know each other very well). She had a few requests for the wedding, one of which was that she be walked down the aisle by my fiance and his father/her husband. My mother has difficulty walking and we had discussed not including mothers in the procession, but I said that it would be okay as my mother is so go with flow about everything.

Thing is, my FMIL will absolutely, 100% not physically be able to walk down the aisle without an incredible struggle and making a scene. She is very obese and has related breathing difficulties and has had recent falls. She uses a motorized scooter when she goes shopping and needs to be picked up/dropped off at the entrance of stores and restaurants. The aisle at the church we are marrying in is VERY long and she knows this. Just last evening we went out to eat, and she had trouble with about a 20 yrd walk, having to stop every few feet to lean on cars to catch her breath. On the day of the wedding, she'll have already had a strenuous day with pictures, climbing up to the trolley, etc. She is well aware of her limitations, but she also loves to be the center of attention and would completely risk causing a massive scene to have her 5 min. We are both only children, so I completely understand why this is important to her. But, we should be able to enjoy our wedding day without worrying if we are going to need an ambulance on standby. I am a nurse, and I've seen how quickly she deteriorates, requiring medical attention. I really don't want to end up at my work on my wedding day when it's completely avoidable 🤷‍♀️. My fiance agrees, but we are concerned with bringing this up with her. She is VERY sensitive and tends to take everything as a slight. She can act very childish, pouting and giving the cold shoulder.

Where both of our mothers have difficulty walking, we figured it would be easier to have them seated ahead of the procession, so that they are comfortable and able to fully enjoy the ceremony without having to recover from their journey down the aisle. My mother is fine with anything, she just wants us to be happy!

Anyone ever experience a similar issue? Any suggestions on an alternative to make her feel special without having her cause a scene or very avoidable medical crisis on our special day? Thank you! 😊