and will be bringing some of his feeding products
This is another wrinkle, in that these (Making an assumption as to what you are talking about) could be considered liquids, running up against container size/total amount of liquids allowed in carry-on.
Yes, many airlines make exceptions for medical needs, and Governments sometimes get involved and pass regulations, but a couple important points not mentioned.
- Security (TSA), will have it's own rules depending on country, this mainly affects you regarding the feeding products, so you may need to look into the four countries to determine security allowances for those. US/TSA rules may be different from Norway (an EEA and Schengen but not EU), Switzerland (Schengen, but not EU) and Italy (Schengen and EU)
- While most airlines have exceptions for medical devices, they do usually focus on assistive devices (wheelchairs, breathing, etc.) needed for safe passage, secondary devices may be considered normal baggage in some cases, so you need to dig a bit beyond just seeing something about medical or assistive devices. Unfortunately, probably you need to contact each airline, find some assistance specifically for disabled passengers (for lack of a better term) and get your questions answered. Unfortunately, much will still come down to the individual security or gate personnel. For an airline like Easyjet, (or any airline) that is just a straight hop, consider checking the items. Lost or delayed luggage is a rarity on these flights.