Coconuts are part of the Aracaceae family of plants so are more similar to palm plants, banana and pineapple than they are to tree nuts. There is little evidence that coconut should be avoided if you suffer from a nut allergy.
Coc n 1 is a major allergen associated with allergy to coconut – it is classified as an inhalent allergen rather than an ingested food allergen.
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Coconut.php
The allergy resources page for coconut covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with coconut.
There is also regularly updated links to useful websites specifically for coconut allergies and the latest research papers on the topic.
If you have multiple allergies and are interested in how they are linked or want to find out more about food allergies outside the usual top 14 then you can follow me on Facebook or Twitter, where I share a food allergy card every day of the week.