9yo now sitting in front seat of car - sibling meltdown AIBU?

[Handywoman]

Ok so dd1 is now tall enough to sit in front seat of car and now asks to do so.

Trouble is her 7yo sister is has gone into total meltdown over the issue (it's... not... FAIIIIRRRR) on school pickup-refusing to get in car, then after bring bundled into car refusing to come in the house blah blah blah.

Ironically I thought separating them in the car might help with the after-school bickering!

I am torn between continuing and allowing dd1 the privilege since she is now tall enough, and reverting because of the upset caused to dd2.

dd2 is being assessed for autism and I can't work out whether this is a characteristic upset at a big change, or an understandable reaction to bring alone in the back of the car.

Thoughts (and perspective) anyone?

Thanks....

Handywoman xxxxx

I would not call it bad behaviour, it just is what it is, influenced by rigidity of thinking, lack of theory of mind and difficulty with change. I managed to push all the buttons for dd2 without adequately preparing her. I did say I was going to talk to them both about it. Which I have, it is not an excuse but requires extra input, and we are working on it!

Thanks, Handywoman x