We ate lots of gf/cf anyway so it was bread mainly that was the big change, plus I cut down then stopped buying stuff like crisps/biscuits and became ultra careful about checking food labels
DS now has a probiotic with omega every day (bio kult infantis)
Animal parade multivitamins, as they don't have sweeteners etc in them
I replaced all bread type stuff with genius bread-DSs fine with this. Other gf breads are pretty grim ime, Genius tastes pretty good
DSs ate gf ham anyway, ditto Youngs gf fish fingers, gf pasta, pure spread, helen brownings speedy sausages (look like chipolatas)
Oatly milk is nicest cf milk I've found-non organic one has added calcium, but i mainly use it for baking, none of my DSs have wanted/liked milk as a drink
I now make a lot of home made chicken stock and cook pasta/rice noodles in it which ds will eat
I have slowly but surely cut out as much processed food as possible-crisps/biscuits/sweets etc as DS was eating these then not having anything much for lunch/supper. DS only eats strawberries atm fruit wise, used to eat apples but has given them up for now
Orgran do nice gf/cf biscuits but again if I buy these DS will eat them and not much else so have to limit. Orgran also do a good gf pizza base mix
I tried making home made fruit juices with a juicer but DS won't drink them
I try and get DS involved with cooking/baking/touching different foods etc
Positives
DS has stopped spitting and seems less aggressive since shortly after going gf/cf and is coping better with interactions with other children/going out and to new places. Fewer meltdowns. These things may have happened anyway without dietary changes I know but I personally have faith in the gf/cf diet. Poos are better (more healthy looking/less offensive smelling)
An unexpected side effect is that DS2's years of constipation were cured overnight when we cut out gluten
No negatives
DS looks healthier to me, is less slender and hasn't become any more picky than before, appetite is better too a lot of the time.
It's early days for us but so far so good
Hope some of the above waffly ramble might be helpful