Marcio_Osorio

I cannot seem to think of a substitute for the parts marked red below.

"[The compound] boy + friend, however, has falling stress. It differs from the first two compounds in not being literal when it does not mean any friend who is a boy."

I gave substituting "being" for "sounding" some consideration but in no way could I produce an acceptable E-P form for "who is a boy" at the end of the sentence. Can you please help me to produce one?