1.) If you solidify with a closed quilt, it will always default to removing the material on the inside of the closed quilt.
2.) Pay attention to the order of your merges. The merged quilt is seen as a continuation of the first quilt added to the merge. It should maintain that quilt's normal direction, name, etc. In your scenario below, quilts 1 and 2 probably have their normal going a different way. Quilt 3 is simply a copy of whatever its parent is. The copy won't change the normal direction. One possible solution might be to create a new quilt before 1 & 2, and use this as your main feature. Merge 1 or 2 to this, and then copy this to 3. Because 1 won't change, the normal in 3 shouldn't change either.
Tom U.