Sentence:  It was not as though she noted clearly that her nephews had not been to see her for ten years , not since their last journey eastward to witness their Uncle Izaak being lowered into the rocky soil ; that aside from due notification of certain major events in their lives ( two marriages , two births , <WSD>one</WSD> divorce ) , Christmas and Easter cards of the traditional sort had been the only thin link she had with them through the widowed years . 
Meaning of the word marked with <WSD> tags:  having the indivisible character of a unit