I haven't had time to check in here lately, but when I saw that your darling daughter needed some stenting done I thought I might post a bit. My son Sean has had 14 cardiac cath/angioplasties, with 4 stents placed. They have helped him tremendously, though it is frustrating that he continues to need further work... are you comfortable with the docs doing the work, or have you considered getting a 2nd opinion elsewhere? Sean has been to several places for his vascular issues, we found the best help at Boston Children's hospital, they were awesome. (though thankfully our local docs in Idaho are also quite good, and are fine for most of his care).
As for seating, I am afraid I wont be of much help. Sean's scoliosis was not found till he was 2, and by 5 he had already had 5 surgeries for grow rods and his first fusion. He is going to be 10 next month, and is doing marvelously well following halo traction and fusion 2 yrs ago in Seattle.
Anyway, will keep your little one in my prayers... let me know if I can help in some way...
Heidi (mom to 3 boys, Sean is 9 and has LCDH, SBS, is TPN, O2, and Bipap dependent, has SVC stenosis/stent x4, severe malignant scoliosis fused twice from T1-L2, halo traction for 2 months, severe restrictive lung disease, a CVL and GT, Fundo x2, and is one of my heroes.)