molestrip, i'm not trying to be an asshole but consider leaving your kids be and not make their childhood about an odyssee to various doctors and biting on useless pieces of plastic.
i have no idea what you look like, but take a look in the mirror and take a look at your wife. if you are both unattractive and if one of you has similar problems as your kids (narrow palate, open bite, mouth breather) then SAVE YOUR MONEY instead of wasting it on childhood treatments which will either not work at all or reverse themselves during puberty anyway.
instead, let your kids have fun while they grow up - no functional ortho appliances, no braces, no bulls**t. save that money, shuttle your daughter at age 15 to a top maxfac and pay to fix whatever genetic horrors you bestowed upon her. this is honestly the best way of doing things, because from what you wrote your daughter will need surgery regardless of what you do now.
just my 2 cents.