A resounding YES , pred. Here in Derby, some years ago we had the resident who went to Israel with a friend and tried to blow himself up in a crowded bar. His bomb failed to go off and his body was found a few days later floating in the Med.
Some Muslim friends of mine told me afterwards, his family threw a big party for him, before he went on "holiday". Apparently they all knew what he was planning (and therefore are all guilty of involvement) Only person ever charged with involvement was his wife, who , unsurprisingly was found not guilty, even though email exchanges between them, showed she knew what he was planning.