URGH - not crossing midline that was the bane of my existence for years and years!!! That's cross lateralization of the brain or lateralization of brain function. Like I and others have said, it's the neurologically wiring. You can improve or enhance it but you cannot put more bits in or connect A to B when the neural pathway goes from say H to P instead.
Ds was born with something like hemiplegia so he didn't have 'normal' use of the left side of his body. Unfortunately for me, this enhanced ds's cognitive abilities in ways I never expected/anticipated and with whatever ds already genetically inherited. Ds learned to compensate extremely well within nanoseconds since he was a baby and this has created a real roller coaster experience with him as a result.
Swimming and/or water therapy can help with lateralization of the brain. Ds had water therapy at 6.5 years old. No one said ds had to be an athlete or suddenly be coordinated, but the ability to swim and be in water therapy was non-negotiable. A lot of water therapy involved making the equivalent movements of snow angels in the water.
Swimming requires the use of both legs and arms and core body muscles. Plus, being the water is more energy efficient and provides more buoyancy or less chance to fudge using both sides of the body and brain. Now at 10, and after many years of getting ds to swim, ds actually enjoys swimming. So there is hope.
Raising both eyebrows independently is a pretty cool trick. How many people could do that? I'm sure there's other cool stuff your dd can do too. Start making a list of them.
Keep focusing on the strengths and don't try to drown in the weaknesses, I say. Try to avoid staring at that midline rabbit hole! Oy vey. Better to flip the negative into something more positive and how the wacky neurological wiring may be a real boon for creativity and life in general. Make light of it and see the funny side of the topsy turvy situation.