myself, my husband, my 14 year old son are travelling to USA. we, however are taking my sons 15 year old friend with us. Can we include him in our insurance? Where can I get an insurance that would cover my family and my sons friend?

I dont think that you will get insurance as you sons friend is not considered a dependant of yours. Does you sons friends parents perhaps have a travel policy that covers him. You would need to check first if he can travel on his own without his parents. If not he could purchase a policy for himself for the duration of the holiday. As he is only 15 his parents would maybe need to sign the application form. For single trip insurance for him try money supermarket or Marks and Spencer is quite competitive aswell.

Good luck