relation coincidence

A few years ago my wife was in a vegetarian restaurant in Shrewsbury during the Easter School holidays , when she came aware of a converation between a very capable granddaughter and her grandmother. About a month later, the only time in her life she has attended Chelsea Flower Show, the aforementioned grandmother was seen by my wife. Then later, on the May Bank Holiday, at the local Church Fete at Wentnor,Shropshire, the self same grandmother appeared on the scene. My wife felt she was being 'haunted' by this woman and so she approached her and the above sequence was confirmed. It transpired she and her husband had recently moved in to the district. I conversed with the husband and upon enquirying about his previous occupation, prior to his retiring, he had been in the Engineering Department of the Union Castle Shipping Line based in their London Office. I then revealed that 2 brothers-in-law of mine worked in the same department and he confirmed that they were, in fact, colleagues. What are the chances of that happening, both the former and the latter?