Just to add the list of things to think about.... Not all of them may be relevant and no individual one will be a magic cure but I find every little things adds to the picture.
Household chemicals - I would ditch the flash wipes and try to keep chemicals as simple as possible
Creams etc : the range of reactions and substances reacted to in this category are vast, anything with petroleum is a no no for DS2
Toothpaste: DS2 rubs his nose when having his teeth cleaned and hates it, changing to a non aluminum and non Sodium Lareth Sulphate one has helped unbelievably and reduced his wheezing.
Food - DS has food intolerences including wheat and dairy (which the latest consultant believes are at the root of all allergies). He is also allergic to peanuts and sesame, we had reintroduced sesame after a negative skin prick test but it seems that was the wrong thing to do, we have now excluded again and he is much better.
Vitamin C is a natural antihistamine and can be given in large doses when she is not well. Also look at her diet for essential fatty acids, coconut oil, borage, walnut, sesame, sunflower, olive, flax seed and fish oils, all provide different elements required for a healthy immune system. Blue tansy essential oil rubbed on the back of his hands has also helped.
Also, worth having a look at Buteko breathing (in and out through the nose basically). Actually relatively easy to teach at this age, put her on her side to sleep and lie beside her with your hand gently under her chin. A few nights will make all the difference. You can also put your hands on her tummy which brings attention to her breath and get her to push your hand out. Get her to lie on the floor on her tummy supported by her hands when playing / watching TV / having stories which will also encourage deep lung breathing.
And finally, osteopathy can loosen up the upper chest area and allow the lungs to properly fill.